fix: release gateway lock before spawning restart child

Move lock.release() before restartGatewayProcessWithFreshPid() so the
spawned child can immediately acquire the lock without racing against
a zombie parent. This eliminates the root cause of the restart loop
where the child times out waiting for a lock held by its now-dead parent.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/cli/gateway-cli/run-loop.ts

@@ -83,6 +83,8 @@ export async function runGatewayLoop(params: {
         clearTimeout(forceExitTimer);
         server = null;
         if (isRestart) {
+          // Release the lock BEFORE spawning so the child can acquire it immediately.
+          await lock?.release();
           const respawn = restartGatewayProcessWithFreshPid();
           if (respawn.mode === "spawned" || respawn.mode === "supervised") {
             const modeLabel =
@@ -90,7 +92,6 @@ export async function runGatewayLoop(params: {
                 ? `spawned pid ${respawn.pid ?? "unknown"}`
                 : "supervisor restart";
             gatewayLog.info(`restart mode: full process restart (${modeLabel})`);
-            await lock?.release();
             cleanupSignals();
             params.runtime.exit(0);
           } else {