fix: drain logs + release PID/lock before watchdog os._exit, drop infographic PNG

C1: The watchdog's os._exit(1) bypassed drain_log_queue() and
remove_pid_file()/release_gateway_runtime_lock() — the three things
_exit_after_graceful_shutdown does before exiting. The watchdog's own
logger.critical('shutdown watchdog fired') was silently dropped because
it was still in the async QueueListener queue when os._exit ran. PID
file and runtime lock were stranded on next boot.

W1: Dropped 2MB infographic PNG — dead asset with zero references in
the repo. Binary blobs in git history are permanent; every clone pays
the cost forever.

Authorship: @HexLab98's commits preserved via rebase-merge.

gateway/shutdown_watchdog.py

@@ -219,6 +219,21 @@ def arm_shutdown_watchdog(
                 stream.flush()
             except Exception:
                 pass
+        # Mirror _exit_after_graceful_shutdown: release PID file + runtime
+        # lock BEFORE the log drain (locks must never be stranded), then
+        # drain the async log queue so the logger.critical above actually
+        # reaches the file before os._exit bypasses atexit. (#66892)
+        try:
+            from gateway.status import remove_pid_file, release_gateway_runtime_lock
+            remove_pid_file()
+            release_gateway_runtime_lock()
+        except Exception:
+            pass
+        try:
+            from hermes_logging import drain_log_queue
+            drain_log_queue(timeout=1.0)
+        except Exception:
+            pass
         os._exit(exit_code)
 
     try: