feat: add missing API endpoints

- Add GET /api/insights/latest (returns latest 10 insights)
- Add GET /api/auth/status (health check endpoint)

These endpoints were called by frontend but returned 404,
causing uncaught promise errors that blocked page loading.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/main.py

@@ -644,6 +644,16 @@ def get_stats(x_profile_id: Optional[str]=Header(default=None), session: dict=De
 # ── AI Insights ───────────────────────────────────────────────────────────────
 import httpx, json
 
+@app.get("/api/insights/latest")
+def get_latest_insights(x_profile_id: Optional[str]=Header(default=None), session: dict=Depends(require_auth)):
+    """Get latest AI insights across all scopes."""
+    pid = get_pid(x_profile_id)
+    with get_db() as conn:
+        cur = get_cursor(conn)
+        cur.execute("SELECT * FROM ai_insights WHERE profile_id=%s ORDER BY created DESC LIMIT 10", (pid,))
+        rows = cur.fetchall()
+        return [r2d(r) for r in rows]
+
 @app.get("/api/ai/insights/{scope}")
 def get_ai_insight(scope: str, x_profile_id: Optional[str]=Header(default=None), session: dict=Depends(require_auth)):
     pid = get_pid(x_profile_id)
@@ -1111,6 +1121,11 @@ def get_me(session: dict=Depends(require_auth)):
     pid = session['profile_id']
     return get_profile(pid, session)
 
+@app.get("/api/auth/status")
+def auth_status():
+    """Health check endpoint."""
+    return {"status": "ok", "service": "mitai-jinkendo", "version": "v9b"}
+
 @app.post("/api/auth/password-reset-request")
 @limiter.limit("3/minute")
 async def password_reset_request(req: PasswordResetRequest, request: Request):