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>

src/config/configuration.ts

@@ -13,6 +13,9 @@ export default () => ({
         webhookSecret: process.env.EXOTEL_WEBHOOK_SECRET ?? '',
     },
     ai: {
+        provider: process.env.AI_PROVIDER ?? 'openai',
         anthropicApiKey: process.env.ANTHROPIC_API_KEY ?? '',
+        openaiApiKey: process.env.OPENAI_API_KEY ?? '',
+        model: process.env.AI_MODEL ?? 'gpt-4o-mini',
     },
 });