feat: /api/settings route - read/write user settings via gateway memory

app/(app)/api/settings/route.ts

@@ -0,0 +1,47 @@
+import { NextResponse } from "next/server";
+
+const GATEWAY = process.env.BLACKROAD_GATEWAY_URL || "http://127.0.0.1:8787";
+const SETTINGS_KEY = "user.settings";
+
+const DEFAULTS = {
+  theme: "dark",
+  defaultAgent: "LUCIDIA",
+  defaultModel: "llama3.2",
+  streamingEnabled: true,
+  memoryEnabled: true,
+  gatewayUrl: GATEWAY,
+};
+
+export async function GET() {
+  try {
+    const r = await fetch(`${GATEWAY}/memory/${SETTINGS_KEY}`, { signal: AbortSignal.timeout(3000) });
+    if (r.ok) {
+      const data = await r.json();
+      return NextResponse.json({ settings: { ...DEFAULTS, ...data.value } });
+    }
+  } catch { /* gateway not available */ }
+  return NextResponse.json({ settings: DEFAULTS });
+}
+
+export async function POST(request: Request) {
+  const body = await request.json();
+  const settings = { ...DEFAULTS, ...body };
+  
+  // Validate
+  const valid = ["dark", "light", "system"].includes(settings.theme)
+    && typeof settings.streamingEnabled === "boolean";
+  if (!valid) {
+    return NextResponse.json({ error: "Invalid settings" }, { status: 400 });
+  }
+
+  try {
+    await fetch(`${GATEWAY}/memory`, {
+      method: "POST",
+      headers: { "Content-Type": "application/json" },
+      body: JSON.stringify({ key: SETTINGS_KEY, value: settings }),
+      signal: AbortSignal.timeout(3000),
+    });
+  } catch { /* non-fatal */ }
+
+  return NextResponse.json({ settings, saved: true });
+}