feat(timeline): draw person-defined symptoms as value lines

A custom symptom could feed pattern discovery and the Coach but could not
be looked at over time. The timeline now offers every symptom the record
has logged, hidden ones included, beside the measurements and lab markers,
and draws a chosen one as a value line.

`values` takes `symptom:<definitionId>`, checked for its shape and capped
like a lab marker; an id the record does not hold draws nothing. A day's
value is its highest intensity on the record's local day; a point is the
mean of the bucket's day values over the days logged, with the number of
those days, and a day without an entry is not a zero. The line sits on a
fixed 0 to 10 scale. Symptoms are read under the illness lane's gate, the
module and sharing domain the symptom routes use. An `all` window reaches
back to a chosen symptom's first entry.

The response carries `symptomSeries` and `availableSymptoms`; the OpenAPI
contract is regenerated. The page words a point's count as days and the
value out of ten. The date-key schema moves to its own module so the
symptom schemas can share it.

docs/api/openapi.yaml

@@ -26948,9 +26948,12 @@ paths:
         - Records
       summary: The record over the years
       description: Lanes of conditions, allergies, medications, vaccinations, visits, lab days, documents and life events, the
-        standing items without a start, and monthly (or finer, by zoom) value series. Empty lanes are not sent; lanes of
-        a switched-off module never are. The `life` lane (life events and travel periods) is the owner's only and is
-        never sent to a delegate. Requires the opt-in `timeline` module.
+        standing items without a start, and monthly (or finer, by zoom) value series, among them the lab markers
+        (`labSeries`, single readings) and the person-defined symptoms (`symptomSeries`, the day's highest intensity
+        averaged over logged days, on a fixed 0 to 10 scale; read only with the illness module on and the illness
+        section visible) named in `values`. Empty lanes are not sent; lanes of a switched-off module never are. The
+        `life` lane (life events and travel periods) is the owner's only and is never sent to a delegate. Requires the
+        opt-in `timeline` module.
       parameters:
         - in: query
           name: zoom
@@ -26979,19 +26982,22 @@ paths:
         - in: query
           name: values
           schema:
-            description: "Comma-separated value series to include, as `MeasurementType` names, `MOOD`, or a lab marker as
-              `lab:<biomarkerId>` (see `availableLabs`). A name given twice counts once, so the list is bounded by the
-              names that exist; an unknown measurement name or a malformed marker key answers 422. At most 24 lab
-              markers are drawn (ids, unlike names, are not a closed set): the first 24 are kept and any further ones
-              left out without an error. A lab marker that is not in the record (deleted, or another record's) is
-              likewise left out of `labSeries`, so a stored choice never breaks the page."
+            description: "Comma-separated value series to include, as `MeasurementType` names, `MOOD`, a lab marker as
+              `lab:<biomarkerId>` (see `availableLabs`), or a person-defined symptom as `symptom:<definitionId>` (see
+              `availableSymptoms`). A name given twice counts once, so the list is bounded by the names that exist; an
+              unknown measurement name or a malformed marker or symptom key answers 422. At most 24 lab markers and 24
+              symptoms are drawn (ids, unlike names, are not a closed set): the first 24 of each are kept and any
+              further ones left out without an error. A lab marker or symptom that is not in the record (deleted, or
+              another record's) is likewise left out of `labSeries` / `symptomSeries`, so a stored choice never breaks
+              the page."
             type: string
-          description: "Comma-separated value series to include, as `MeasurementType` names, `MOOD`, or a lab marker as
-            `lab:<biomarkerId>` (see `availableLabs`). A name given twice counts once, so the list is bounded by the
-            names that exist; an unknown measurement name or a malformed marker key answers 422. At most 24 lab markers
-            are drawn (ids, unlike names, are not a closed set): the first 24 are kept and any further ones left out
-            without an error. A lab marker that is not in the record (deleted, or another record's) is likewise left out
-            of `labSeries`, so a stored choice never breaks the page."
+          description: "Comma-separated value series to include, as `MeasurementType` names, `MOOD`, a lab marker as
+            `lab:<biomarkerId>` (see `availableLabs`), or a person-defined symptom as `symptom:<definitionId>` (see
+            `availableSymptoms`). A name given twice counts once, so the list is bounded by the names that exist; an
+            unknown measurement name or a malformed marker or symptom key answers 422. At most 24 lab markers and 24
+            symptoms are drawn (ids, unlike names, are not a closed set): the first 24 of each are kept and any further
+            ones left out without an error. A lab marker or symptom that is not in the record (deleted, or another
+            record's) is likewise left out of `labSeries` / `symptomSeries`, so a stored choice never breaks the page."
       responses:
         "200":
           description: The timeline for the requested zoom and window.
@@ -94385,6 +94391,19 @@ components:
             $ref: "#/components/schemas/TimelineLabMarker"
           description: Every lab marker this record has a numeric reading for, whatever the window, when the caller may see labs.
             Each may be named in `values` by its `key`.
+        symptomSeries:
+          type: array
+          items:
+            $ref: "#/components/schemas/TimelineSymptomSeries"
+          description: The person-defined symptoms named in `values`, in the order named, each averaged per `bucket` over the days
+            it was logged. A symptom named but not found in the record is left out.
+        availableSymptoms:
+          type: array
+          items:
+            $ref: "#/components/schemas/TimelineSymptomOption"
+          description: Every person-defined symptom this record has logged at least once, hidden ones included (their history is
+            kept), in the record's own order, when the caller may see illness data. Each may be named in `values` by its
+            `key`.
         notable:
           type: array
           items:
@@ -94414,6 +94433,8 @@ components:
         - availableSeries
         - labSeries
         - availableLabs
+        - symptomSeries
+        - availableSymptoms
         - notable
       additionalProperties: false
     TimelineItem:
@@ -94590,6 +94611,104 @@ components:
         - panel
         - unit
       additionalProperties: false
+    TimelineSymptomSeries:
+      type: object
+      properties:
+        key:
+          type: string
+          description: "`symptom:<definitionId>`, as named in `values`."
+        definitionId:
+          type: string
+        label:
+          description: The person's own name for the symptom. Null when it cannot be read; the client words a stand-in.
+          type:
+            - string
+            - "null"
+        icon:
+          description: The symptom's icon name; null for the default glyph.
+          type:
+            - string
+            - "null"
+        isActive:
+          type: boolean
+          description: "False for a hidden symptom: no longer offered for entry, its history kept and drawn."
+        scale:
+          type: object
+          properties:
+            min:
+              type: number
+              const: 0
+            max:
+              type: number
+              const: 10
+          required:
+            - min
+            - max
+          additionalProperties: false
+          description: The fixed scale the line is drawn on, the intensity scale, whatever the window holds.
+        points:
+          type: array
+          items:
+            $ref: "#/components/schemas/TimelineSymptomPoint"
+          description: Buckets of the response's `bucket` with at least one logged day, oldest first. A bucket without one is
+            absent, never zero and never interpolated.
+      required:
+        - key
+        - definitionId
+        - label
+        - icon
+        - isActive
+        - scale
+        - points
+      additionalProperties: false
+    TimelineSymptomPoint:
+      type: object
+      properties:
+        t:
+          type: string
+          description: The bucket's first day.
+        mean:
+          type: number
+          minimum: 0
+          maximum: 10
+          description: The mean of the bucket's day values over the days the symptom was logged. A day's value is the highest
+            intensity (0 to 10) logged on it; a day without an entry is not a zero and does not count.
+        count:
+          type: integer
+          minimum: 1
+          maximum: 9007199254740991
+          description: Days the symptom was logged in the bucket, the days behind the mean. Clients draw a point from fewer than
+            three as thin.
+      required:
+        - t
+        - mean
+        - count
+      additionalProperties: false
+    TimelineSymptomOption:
+      type: object
+      properties:
+        key:
+          type: string
+          description: "`symptom:<definitionId>`, to name in `values`."
+        definitionId:
+          type: string
+        label:
+          type:
+            - string
+            - "null"
+        icon:
+          type:
+            - string
+            - "null"
+        isActive:
+          type: boolean
+      required:
+        - key
+        - definitionId
+        - label
+        - icon
+        - isActive
+      additionalProperties: false
     TimelineReadinessEnvelope:
       type: object
       properties: