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/lib/localDb.js

@@ -57,7 +57,10 @@ const defaultData = {
     observabilityMaxRecords: 1000,
     observabilityBatchSize: 20,
     observabilityFlushIntervalMs: 5000,
-    observabilityMaxJsonSize: 1024
+    observabilityMaxJsonSize: 1024,
+    outboundProxyEnabled: false,
+    outboundProxyUrl: "",
+    outboundNoProxy: ""
   },
   pricing: {} // NEW: pricing configuration
 };
@@ -72,15 +75,18 @@ function cloneDefaultData() {
     apiKeys: [],
     settings: {
       cloudEnabled: false,
-    tunnelEnabled: false,
-    tunnelUrl: "",
+      tunnelEnabled: false,
+      tunnelUrl: "",
       stickyRoundRobinLimit: 3,
       requireLogin: true,
       observabilityEnabled: true,
       observabilityMaxRecords: 1000,
       observabilityBatchSize: 20,
       observabilityFlushIntervalMs: 5000,
-      observabilityMaxJsonSize: 1024
+      observabilityMaxJsonSize: 1024,
+      outboundProxyEnabled: false,
+      outboundProxyUrl: "",
+      outboundNoProxy: "",
     },
     pricing: {},
   };
@@ -114,7 +120,17 @@ function ensureDbShape(data) {
     ) {
       for (const [settingKey, settingDefault] of Object.entries(defaultValue)) {
         if (next.settings[settingKey] === undefined) {
-          next.settings[settingKey] = settingDefault;
+          // Backward-compat: if users previously saved a proxy URL,
+          // default to enabled so behavior doesn't silently change.
+          if (
+            settingKey === "outboundProxyEnabled" &&
+            typeof next.settings.outboundProxyUrl === "string" &&
+            next.settings.outboundProxyUrl.trim()
+          ) {
+            next.settings.outboundProxyEnabled = true;
+          } else {
+            next.settings[settingKey] = settingDefault;
+          }
           changed = true;
         }
       }