feat(coach): keep stored reminders readable and erasable with the Coach unavailable

Reminders are the person's own record, like the stored facts,
conversations and plans. The list and delete routes no longer ask the
Coach module; creating, confirming, resolving or rescheduling one stays
Coach use and is refused by POST and PATCH as before.

Settings -> Coach now always mounts the reminders card (shown with Hide
Coach on only when reminders exist), and Settings -> AI lists them through
the stored-memory block while Settings -> Coach is out of reach. With the
Coach unavailable the card is read-only: every reminder can be read and
deleted, while keep / done / dismiss are not offered.

src/app/api/__tests__/module-route-gate-inventory.test.ts

@@ -330,6 +330,11 @@ const EXEMPT_ROUTES: ReadonlyArray<string> = [
   // The stored plans list. Its sibling `[id]` route keeps the Coach gate on
   // PATCH (confirming a proposal is Coach use) and erases without it.
   "src/app/api/coach/plans/route.ts",
+  // Not listed, by the same rule: `coach/reminders/route.ts` lists without the
+  // Coach gate but keeps it on POST (creating one is Coach use), and
+  // `coach/reminders/[id]/route.ts` erases without it but keeps it on PATCH.
+  // Both files still carry a gate, so the walk counts them as gated and an
+  // entry here would fail the "does not hide a gate" check below.
   "src/app/api/insights/chat/[id]/route.ts",
   "src/app/api/insights/chat/messages/[id]/feedback/route.ts",
   // The Today digest and its dismiss: data, with the AI parts masked by the