Feat: add env-driven LLM configuration and smoke test

package.json

@@ -13,6 +13,7 @@
     "test": "vitest run",
     "test:go": "cd media && go test ./... && go build ./...",
     "test:e2e": "playwright test",
+    "test:llm": "tsx scripts/llm-smoke.ts",
     "verify": "pnpm check && pnpm test && pnpm test:go && pnpm build && pnpm test:e2e",
     "db:push": "drizzle-kit generate && drizzle-kit migrate"
   },