feat: add AI settings routes, storage, UI card, and migration

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

apps/Backend/src/routes/ai-settings.ts

@@ -0,0 +1,39 @@
+import express, { Request, Response } from "express";
+import { storage } from "../storage";
+
+const router = express.Router();
+
+// GET /api/ai/settings
+router.get("/settings", async (req: Request, res: Response): Promise<any> => {
+  try {
+    const userId = req.user?.id;
+    if (!userId) return res.status(401).json({ message: "Unauthorized" });
+
+    const settings = await storage.getAiSettings(userId);
+    if (!settings) return res.status(200).json(null);
+
+    return res.status(200).json({ id: settings.id, apiKey: settings.apiKey });
+  } catch (err) {
+    return res.status(500).json({ error: "Failed to fetch AI settings", details: String(err) });
+  }
+});
+
+// PUT /api/ai/settings
+router.put("/settings", async (req: Request, res: Response): Promise<any> => {
+  try {
+    const userId = req.user?.id;
+    if (!userId) return res.status(401).json({ message: "Unauthorized" });
+
+    const { apiKey } = req.body;
+    if (!apiKey?.trim()) {
+      return res.status(400).json({ message: "apiKey is required" });
+    }
+
+    const settings = await storage.upsertAiSettings(userId, apiKey.trim());
+    return res.status(200).json({ id: settings.id, apiKey: settings.apiKey });
+  } catch (err) {
+    return res.status(500).json({ error: "Failed to save AI settings", details: String(err) });
+  }
+});
+
+export default router;