feat(proxy): add outbound HTTP proxy support for OAuth + provider requests

- Patch Node fetch via undici ProxyAgent when HTTP_PROXY/HTTPS_PROXY/ALL_PROXY is set
- Ensure proxy patch is loaded for both chat pipeline and OAuth token exchange
- Add Dashboard Settings → Network to edit outbound proxy and apply immediately
- Persist outbound proxy settings in local db and initialize on server startup
- Move proxy helpers to src/lib/network/ for better structure
- Rename src/proxy.js → src/dashboardGuard.js to avoid naming confusion
- Re-apply proxy env after DB import
- Fix: close old dispatcher on proxy URL change to prevent connection pool leak
- Fix: idempotency guard to avoid patching globalThis.fetch multiple times

Made-with: Cursor

src/app/api/settings/route.js

@@ -1,5 +1,6 @@
 import { NextResponse } from "next/server";
 import { getSettings, updateSettings } from "@/lib/localDb";
+import { applyOutboundProxyEnv } from "@/lib/network/outboundProxy";
 import bcrypt from "bcryptjs";
 
 export async function GET() {
@@ -53,6 +54,15 @@ export async function PATCH(request) {
     }
 
     const settings = await updateSettings(body);
+
+    // Apply outbound proxy settings immediately (no restart required)
+    if (
+      Object.prototype.hasOwnProperty.call(body, "outboundProxyEnabled") ||
+      Object.prototype.hasOwnProperty.call(body, "outboundProxyUrl") ||
+      Object.prototype.hasOwnProperty.call(body, "outboundNoProxy")
+    ) {
+      applyOutboundProxyEnv(settings);
+    }
     const { password, ...safeSettings } = settings;
     return NextResponse.json(safeSettings);
   } catch (error) {