feat: migrate AI to Vercel AI SDK, add OpenAI provider, fix worklist

- Replace raw @anthropic-ai/sdk with Vercel AI SDK (generateText, tool, generateObject)
- Add provider abstraction (ai-provider.ts) — swap OpenAI/Anthropic via env var
- AI chat controller: dynamic KB from platform (clinics, packages, insurance), zero hardcoding
- AI enrichment service: use generateObject with Zod schema instead of manual JSON parsing
- Worklist: resolve agent name from platform currentUser API instead of JWT decode
- Worklist: fix GraphQL field names to match platform remapping (source, status, direction, etc.)
- Config: add AI_PROVIDER, AI_MODEL, OPENAI_API_KEY env vars

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

package.json

@@ -20,13 +20,15 @@
     "test:e2e": "jest --config ./test/jest-e2e.json"
   },
   "dependencies": {
-    "@anthropic-ai/sdk": "^0.79.0",
+    "@ai-sdk/anthropic": "^3.0.58",
+    "@ai-sdk/openai": "^3.0.41",
     "@nestjs/common": "^11.0.1",
     "@nestjs/config": "^4.0.3",
     "@nestjs/core": "^11.0.1",
     "@nestjs/platform-express": "^11.0.1",
     "@nestjs/platform-socket.io": "^11.1.17",
     "@nestjs/websockets": "^11.1.17",
+    "ai": "^6.0.116",
     "axios": "^1.13.6",
     "reflect-metadata": "^0.2.2",
     "rxjs": "^7.8.1",
@@ -54,6 +56,7 @@
     "ts-loader": "^9.5.2",
     "ts-node": "^10.9.2",
     "tsconfig-paths": "^4.2.0",
+    "tsx": "^4.21.0",
     "typescript": "^5.7.3",
     "typescript-eslint": "^8.20.0"
   },