fix: sequential port probes and corrected test for non-required port overflow

- backendPort.ts: Replace concurrent Promise.all host probes with sequential
  loop to prevent EADDRINUSE self-interference when overlapping addresses
  (e.g. 127.0.0.1 and 0.0.0.0) bind to the same port simultaneously.

- dev-runner.test.ts: Fix 'allows offsets where only non-required ports exceed
  max' test to actually exercise the edge case with the new BASE_SERVER_PORT.
  Use offset 51763 with requireServerPort=false/requireWebPort=true so the
  server port (65536) exceeds MAX_PORT while the web port (57496) stays in range.

Author: cursoragent

apps/desktop/src/backendPort.ts

@@ -58,10 +58,14 @@ export async function resolveDesktopBackendPort({
   // Keep desktop startup predictable across app restarts by probing upward from
   // the same preferred port instead of picking a fresh ephemeral port.
   for (let port = startPort; port <= maxPort; port += 1) {
-    const availability = await Promise.all(
-      hostsToCheck.map((candidateHost) => canListenOnHost(port, candidateHost)),
-    );
-    if (availability.every(Boolean)) {
+    let allAvailable = true;
+    for (const candidateHost of hostsToCheck) {
+      if (!(await canListenOnHost(port, candidateHost))) {
+        allAvailable = false;
+        break;
+      }
+    }
+    if (allAvailable) {
       return port;
     }
   }

scripts/dev-runner.test.ts

@@ -246,13 +246,13 @@ it.layer(NodeServices.layer)("dev-runner", (it) => {
     it.effect("allows offsets where only non-required ports exceed max", () =>
       Effect.gen(function* () {
         const offset = yield* findFirstAvailableOffset({
-          startOffset: 51_762,
-          requireServerPort: true,
-          requireWebPort: false,
+          startOffset: 51_763,
+          requireServerPort: false,
+          requireWebPort: true,
           checkPortAvailability: () => Effect.succeed(true),
         });
 
-        assert.equal(offset, 51_762);
+        assert.equal(offset, 51_763);
       }),
     );
   });