feat(illness): add the condition-journal MVP behind a born-gated module

Introduce a retrospective illness/condition journal: episodes with a
lifecycle (acute / chronic-ongoing / recurring / flare) and a daily
symptom timeline forked structurally from the cycle log-day surface. The
journal is a record, not a medical device — no prediction or diagnosis UI.

- Register `illness` as a born-gated (opt-in / default-off) module. The
  gate resolver flips the disabled-allowlist default to off for born-gated
  keys, so the surface stays dark until the account opts in from the
  Modules hub. `isIllnessEnabled` + `requireIllnessEnabled` delegate to the
  module foundation (one source of truth) and re-stamp an illness errorCode.
- Episode CRUD under /api/illness: list / create / get / edit / resolve /
  delete, plus a per-episode-day day-log upsert on (episodeId, date). Every
  route wraps apiHandler, Zod-validates with returnAllZodIssues, narrows
  userId from auth, builds data field-by-field, and gates the module.
  Free-text notes encrypt at rest through the shared Bytes codec.
- Log-day sheet (cycle fork): ~8 Jackson/WURSS symptom chips 0-3 + a
  functional-impact group + fever + an encrypted note, one row per day.
- Episode history page + a born-gated nav entry, neutral palette, status
  via a neutral Badge, retrospective-only copy. i18n across all six locales.
- Cover the new routes in the module-route-gate inventory; unit tests for
  the day-log upsert, the gate enforcement, and the born-gated resolver.

The /api/auth/me module map now projects the `illness` flag (openapi.yaml
regenerated).

src/lib/validations/illness.ts

@@ -0,0 +1,135 @@
+/**
+ * Illness / condition-journal request/response validation (v1.18.1).
+ *
+ * Source of truth for the `/api/illness/*` wire contract. The Zod schemas
+ * here are reused by the OpenAPI registry so the spec stays single-source.
+ * `userId` is NEVER a body field — it is narrowed from the session/Bearer
+ * in every route and fed to the Prisma `where`.
+ *
+ * The journal is a CONDITION journal (any illness/condition kept for
+ * oneself), retrospective-only — NEVER a predictor/diagnoser. Day-log
+ * dates are `YYYY-MM-DD` strings (the CycleDayLog / MoodEntry tz-anchored
+ * convention); instants are ISO-8601 with offset. Free-text notes are
+ * encrypted at rest (`noteEncrypted` Bytes column); every other field is
+ * queryable plaintext.
+ */
+import { z } from "zod/v4";
+import { isPlausibleEntryInstant } from "@/lib/validations/entry-instant";
+
+/**
+ * Plausible-instant bound shared with the measurement / mood / cycle
+ * paths: no future instant beyond the 5-min skew, no instant before 1900.
+ * Stays a string on the wire (iOS reads it back verbatim).
+ */
+const boundedInstant = z.iso
+  .datetime({ offset: true })
+  .refine((s) => isPlausibleEntryInstant(new Date(s)), {
+    message: "must be a plausible instant (not future, not pre-1900)",
+  });
+
+const dateString = z
+  .string()
+  .regex(/^\d{4}-\d{2}-\d{2}$/, "Expected a YYYY-MM-DD date");
+
+/* ── enums (mirror the Prisma enums) ─────────────────────────────── */
+
+export const illnessTypeEnum = z.enum([
+  "INFECTION",
+  "ALLERGY",
+  "INJURY",
+  "MENTAL_HEALTH",
+  "AUTOIMMUNE",
+  "CHRONIC",
+  "OTHER",
+]);
+
+export const illnessLifecycleEnum = z.enum([
+  "ACUTE",
+  "CHRONIC_ONGOING",
+  "RECURRING",
+  "FLARE",
+]);
+
+/* ── episode CRUD ─────────────────────────────────────────────────── */
+
+/**
+ * Create an episode. `label` is the user-facing name; `note` is encrypted
+ * at rest. `parentConditionId` threads a FLARE/RECURRING bout under a
+ * parent condition. `onsetAt` defaults to "now" server-side when omitted.
+ */
+export const illnessEpisodeCreateSchema = z.object({
+  label: z.string().min(1).max(120),
+  type: illnessTypeEnum,
+  lifecycle: illnessLifecycleEnum.optional().default("ACUTE"),
+  onsetAt: boundedInstant.optional(),
+  resolvedAt: boundedInstant.nullable().optional(),
+  parentConditionId: z.string().min(1).max(40).nullable().optional(),
+  note: z.string().max(2000).nullable().optional(),
+});
+
+export type IllnessEpisodeCreate = z.infer<typeof illnessEpisodeCreateSchema>;
+
+/**
+ * Edit an episode — every field optional; an omitted field is left
+ * untouched. A `null` `resolvedAt` re-opens a resolved episode.
+ */
+export const illnessEpisodeUpdateSchema = z
+  .object({
+    label: z.string().min(1).max(120).optional(),
+    type: illnessTypeEnum.optional(),
+    lifecycle: illnessLifecycleEnum.optional(),
+    onsetAt: boundedInstant.optional(),
+    resolvedAt: boundedInstant.nullable().optional(),
+    parentConditionId: z.string().min(1).max(40).nullable().optional(),
+    note: z.string().max(2000).nullable().optional(),
+  })
+  .strict();
+
+export type IllnessEpisodeUpdate = z.infer<typeof illnessEpisodeUpdateSchema>;
+
+/** Resolve (mark recovered) — a dedicated PATCH `/resolve` endpoint. */
+export const illnessEpisodeResolveSchema = z.object({
+  resolvedAt: boundedInstant.optional(),
+});
+
+export type IllnessEpisodeResolve = z.infer<
+  typeof illnessEpisodeResolveSchema
+>;
+
+/** History/list query — newest-first, bounded. */
+export const illnessEpisodeListQuerySchema = z.object({
+  limit: z.coerce.number().int().min(1).max(100).optional(),
+  includeResolved: z
+    .union([z.literal("true"), z.literal("false")])
+    .optional(),
+});
+
+/* ── day-log capture (one row per day of an episode) ─────────────── */
+
+/**
+ * The canonical day-log input for an episode. Upserts on the
+ * `(episodeId, date)` key. `note` is encrypted at rest (`noteEncrypted`);
+ * `functionalImpact` (0–3) and `feverC` are queryable plaintext. Symptoms
+ * carry a 0–3 Jackson/WURSS severity on the link.
+ */
+export const illnessDayLogInputSchema = z.object({
+  date: dateString,
+  functionalImpact: z.number().int().min(0).max(3).nullable().optional(),
+  feverC: z.number().min(30).max(45).nullable().optional(),
+  symptoms: z
+    .array(
+      z.object({
+        key: z.string().min(1).max(80),
+        severity: z.number().int().min(0).max(3).optional(),
+      }),
+    )
+    .max(40)
+    .optional(),
+  note: z.string().max(2000).nullable().optional(),
+  loggedAt: boundedInstant.optional(),
+});
+
+export type IllnessDayLogInput = z.infer<typeof illnessDayLogInputSchema>;
+
+/** The single-day read query: `GET .../day-logs?date=YYYY-MM-DD`. */
+export const illnessDayLogQuerySchema = z.object({ date: dateString });