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/app/illness/page.tsx

@@ -0,0 +1,46 @@
+"use client";
+
+import { useEffect } from "react";
+import { useRouter } from "next/navigation";
+import { Loader2 } from "lucide-react";
+
+import { useAuth } from "@/hooks/use-auth";
+import { IllnessView } from "@/components/illness/illness-view";
+
+/**
+ * v1.18.1 — the illness / condition-journal entry.
+ *
+ * Born-gated on the resolved `modules.illness` flag from `GET /api/auth/me`
+ * (opt-in / default-off; the per-user opt-in AND the operator server-wide
+ * kill-switch). An unauthenticated visitor is bounced to login; an
+ * authenticated account without the module opted in is bounced home (the
+ * nav entry is already hidden for them, so this only catches a direct URL
+ * hit). Every `/api/illness/*` route also enforces the gate server-side,
+ * so this is a UX redirect, not the security boundary.
+ */
+export default function IllnessPage() {
+  const { user, isLoading, isAuthenticated } = useAuth();
+  const router = useRouter();
+
+  // Born-gated: enabled ONLY when the resolved map says `true`.
+  const enabled = user?.modules?.illness === true;
+
+  useEffect(() => {
+    if (isLoading) return;
+    if (!isAuthenticated) {
+      router.push("/auth/login");
+    } else if (!enabled) {
+      router.push("/");
+    }
+  }, [isLoading, isAuthenticated, enabled, router]);
+
+  if (isLoading || !isAuthenticated || !enabled) {
+    return (
+      <div className="flex h-64 items-center justify-center">
+        <Loader2 className="text-primary h-8 w-8 animate-spin motion-reduce:animate-none" />
+      </div>
+    );
+  }
+
+  return <IllnessView />;
+}