Kill design-only mock surfaces + wire real offline indicator

P1 — cut showcases:
- Delete gallery.tsx (Primitives) and StatesScreen/Specimen from states.tsx
  (keep the reusable EmptyState/OfflineBanner/ModelAwayState).
- Delete placeholder-screen.tsx ('built in a later phase' stub).
- app-shell: drop the states/primitives views, the dev-rail block, the
  PHASE/TITLE maps, the INBOX_UNREAD=3 fixture fallback, and the now-dead demo state.

P2 — real connectivity:
- Replace the fake 'toggle the connection (demo)' button with a live status dot
  derived from the reconcile: green online, red when serving the stale cache
  (gitea unreachable), amber while connecting. OfflineBanner + chat offline now
  reflect real state, not a manual toggle.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/core/src/index.ts

@@ -11,6 +11,8 @@ export type { EstimateLabel, LabelFacts, PriorityLabel } from './labels/label-sc
 
 export { createGiteaClient, normalizeIssue, normalizeMilestone, normalizeTimeline } from './gitea/client.js'
 export type { GiteaClient, ListIssuesOptions } from './gitea/client.js'
+export { discoverRepos } from './gitea/discover.js'
+export type { DiscoveredRepos } from './gitea/discover.js'
 export { GiteaApiError } from './gitea/types.js'
 export type {
   FetchLike,