feat(hub): capability connection admin API + UI (ADR-0027)

Adds the admin surface for managing org-scoped capability credentials,
so operators can configure the Aliyun docmind AccessKey from the web UI
instead of needing a CLI or database access.

Backend:
- CapabilityConnectionService: rotate/list/read/disable, mirroring
  FeishuApplicationConnectionService but keyed by (orgId, capabilityId)
- capabilityReadiness: probeDocmindCredential validates the AccessKey by
  calling QueryDocParserStatus with a dummy id (400 = auth ok, 401/403 = bad)
- Admin routes: GET/PUT/DELETE /api/org/:slug/capability-connections/:capId
  + GET list, wired into orgRoutes

Frontend:
- api.ts: CapabilityConnection type + capabilityConnections/rotate/disable
  client methods
- /admin/org/:slug/capabilities page: lists known capabilities
  (pdf_to_md_bundle, audio_video_to_text), shows status/version/keyId,
  inline rotate/disable forms with AccessKey ID/Secret/Endpoint fields
- Nav item '能力' added to sidebar

Version bump 0.0.31 → 0.0.32.

hub/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@paradigm/hub",
-  "version": "0.0.31",
+  "version": "0.0.32",
   "private": true,
   "type": "module",
   "engines": {