wip: AI chat streaming endpoint + useChat integration (protocol mismatch)

- Server: POST /api/ai/stream using streamText with tools (lookup_patient, lookup_appointments, lookup_doctor)
- Frontend: AiChatPanel rewritten with @ai-sdk/react useChat hook
- Tool result cards: PatientCard, AppointmentCard, DoctorCard
- Streaming works server-side but useChat v1 doesn't parse AI SDK v6 toTextStreamResponse format
- Context panel layout needs redesign — context section fills entire panel, chat pushed below fold
- TODO: Fix streaming protocol, redesign panel layout with collapsible context

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

package.json

@@ -9,6 +9,7 @@
         "preview": "vite preview"
     },
     "dependencies": {
+        "@ai-sdk/react": "^1.2.12",
         "@fortawesome/fontawesome-svg-core": "^7.2.0",
         "@fortawesome/free-solid-svg-icons": "^7.2.0",
         "@fortawesome/pro-duotone-svg-icons": "^7.2.0",