feat: serve the day, its index, the timeline and life events

Replace the day, timeline and life-event stubs with their implementations
(#613) and drop the not-implemented helper, its error code and its OpenAPI
response with the last stub.

loadDay reads one local day for every reader: the readings live inside the
record's own day window (never the UTC rollups), through the canonical-source
engine the mood sheet already uses (resolveDayReadings in linked-context.ts),
with the person's usual range over the 30 days before; the record sections
from their own tables, each in the storage form it speaks (an instant in the
local window, a date string with its own zone, a calendar date). A switched-off
module's section is not read; a section the grant does not cover is named
not_shared and not read.

The day, the day index and the new visit preparation (GET /api/day/notable)
are admitted on the readings and narrowed per section through
actingDomainVisibility, so a scoped grant sees exactly its sections. The
timeline and its readiness stay whole-record reads and narrow their lanes the
same way.

Notable days are deterministic keys: a three-month high or low with history
behind it, a first reading, and in the visit preparation a regular reading
that stopped. The timeline lays out spans and points from the owning tables,
standing items without a date, and series by zoom: months from the rollup
tier inside its five-year window and from one cached live query before it.
The readiness inventory rates each lane with one link per gap.

Life events are created, edited and soft-deleted as MANAGE verbs with audit
rows, encrypted at rest, and join the sharing guard and the handler matrix.
get_day reads a day for the Coach and the MCP endpoint without life events,
notes or document names; its step carries the date it read.

src/components/insights/coach-panel/turn-activity.tsx

@@ -40,6 +40,7 @@ import {
   Brain,
   ChartLine,
   ChartScatter,
+  CalendarDays,
   CloudSun,
   ChevronDown,
   CircleStop,
@@ -275,6 +276,8 @@ export function stepIcon(
       return ChartScatter;
     case "get_environment":
       return CloudSun;
+    case "get_day":
+      return CalendarDays;
     case "get_metric_table":
       return Table2;
     default: