feat(cycle): user-defined custom symptoms

Mirror the v1.13 custom-mood-tag CRUD for cycle symptoms. A user can mint
their own symptoms beyond the 15 seeded ones, picked from a label + icon
popover via a dashed ghost-chip in the log-day sheet's symptom grid.

- POST/GET /api/cycle/symptoms/custom and PATCH/DELETE on /[key]: mint a
  custom:<uuid> key, encrypt the free-text label at rest (AES-256-GCM),
  per-user cap, owner-scoped, gated behind requireCycleEnabled. Soft-hide by
  default, hard-purge on ?purge=true.
- The day-log write already resolves a symptom key against the catalogue plus
  the caller's own rows, so a custom: key links by construction.
- The log-day sheet fetches the user's customs and merges them under a new
  custom category in the chip grid; the ghost-chip + popover reuse the chip
  styling and the Lucide icon set.
- Seed the global custom symptom category (migration 0134).
- The purge route (DELETE /api/cycle/all) now drops the user's custom symptom
  rows too, so no intent-revealing label survives a purge.
- The label is never logged: only the icon + counts reach annotate/auditLog.
- i18n: cycle.symptom.custom.* across all six locales.

src/lib/query-keys.ts

@@ -518,6 +518,9 @@ export const queryKeys = {
   cyclePrefs: () => ["cycle", "prefs"] as const,
   cycleInsights: () => ["cycle", "insights"] as const,
   cycleDayLog: (date: string) => ["cycle", "day-log", date] as const,
+  /** The caller's own custom symptoms (decrypted labels) the log-day sheet
+   * merges into the seeded chip grid. */
+  cycleCustomSymptoms: () => ["cycle", "custom-symptoms"] as const,
 };
 
 /**