fix(providers): time out connection tests and guard undefined names

Apply a 15s AbortSignal timeout in fetchWithConnectionProxy when the
caller supplies none, so provider connection tests stop hanging and
exhausting the browser socket pool. Also make matchSearch return false
for falsy provider names instead of crashing the providers page.

src/app/api/providers/[id]/test/testUtils.js

@@ -445,6 +445,12 @@ async function testOAuthConnection(connection, effectiveProxy = null) {
 }
 
 async function fetchWithConnectionProxy(url, options = {}, effectiveProxy = null) {
+  // Add a 15-second timeout to prevent connection testing from hanging indefinitely
+  // and exhausting the browser/Node.js connection pools.
+  if (!options.signal) {
+    options.signal = AbortSignal.timeout(15000);
+  }
+
   // Vercel relay: forward via relay URL
   if (effectiveProxy?.vercelRelayUrl) {
     const { proxyAwareFetch } = await import("open-sse/utils/proxyFetch.js");