feat(V1-API): implement TREX-Basic consumer API contract with encryption and persistence

- Add V1 API endpoints: assets, ledger, user-info
- Implement Fernet-based credential payload encryption (req-010)
- Extend health response schema with runtime info (req-004)
- Add service token runtime ID issuance (req-005)
- Implement database schema migration for V1 API (req-009)
- Add comprehensive test coverage for V1 endpoints
- Update SRS with 10 new requirements (REQ-004 through REQ-011)
- Create batch planning, design, and verification for BAT-001
- Integrate review-discovery StagePilot skill
- Update documentation indices and baseline specs

app/api/health.py

@@ -1,10 +1,32 @@
 """Health and readiness endpoints."""
 
+from __future__ import annotations
+
+from datetime import datetime, timezone, timedelta
+
 from fastapi import APIRouter
+from pydantic import BaseModel
+
+from app.core.config import get_settings
 
 router = APIRouter(tags=["health"])
 
+_KST = timezone(timedelta(hours=9))
 
-@router.get("/health")
-def healthcheck() -> dict[str, str]:
-    return {"status": "ok"}
+
+class HealthResponse(BaseModel):
+    status: str
+    service: str
+    version: str
+    checked_at: str
+
+
+@router.get("/health", response_model=HealthResponse)
+def healthcheck() -> HealthResponse:
+    settings = get_settings()
+    return HealthResponse(
+        status="ok",
+        service="portfolio-hub",
+        version=settings.app_version,
+        checked_at=datetime.now(_KST).isoformat(),
+    )