feat: in-app support form with email + Gitea issue integration (v0.49.0)

Users can now report bugs, suggestions, or questions from a new /support
page. Each submission sends a confirmation email and, when GITEA_URL/
GITEA_TOKEN/GITEA_REPO are configured in admin Settings, opens a labeled
issue on that repo automatically (best-effort — failure doesn't block the
ticket). Admins get a Support section to triage status and retry failed
Gitea issue creation.

New support_tickets table, gitea.ts client, site-settings entries for the
three new secrets, and OpenAPI docs for the two user-facing endpoints.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/web/app/api/v1/admin/settings/route.ts

@@ -20,6 +20,9 @@ const ALLOWED_KEYS: SiteSettingKey[] = [
   "DEFAULT_VISION_MODEL",
   "DEFAULT_MEAL_PLAN_PROVIDER",
   "DEFAULT_MEAL_PLAN_MODEL",
+  "GITEA_URL",
+  "GITEA_TOKEN",
+  "GITEA_REPO",
 ];
 
 async function requireAdmin() {