feat(GRO-106): portal Communication tab — real backend

- Added GET /portal/conversation and GET /portal/conversation/messages endpoints
- Created Communication.api.ts with typed fetchers and React hooks
- Rewired Communication.tsx to use real API, removed mock data
- Added composer-disabled bar with "Reply from your phone" tooltip
- Added conversation route tests to portal.test.ts

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

packages/db/migrations/meta/_journal.json

@@ -218,6 +218,13 @@
       "when": 1775828067192,
       "tag": "0030_messaging",
       "breakpoints": true
+    },
+    {
+      "idx": 31,
+      "version": "7",
+      "when": 1778732072097,
+      "tag": "0031_steady_veda",
+      "breakpoints": true
     }
   ]
 }