Fix zombie daemon blocking ORB restart in ORBDaemonController

os.kill(pid, 0) returns success for zombie (defunct) processes.
Added ps stat check — if process is in Z state, treat as dead and
clean up PID file so subsequent start() calls work correctly.

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

apps/web/orb_trading_service.py

@@ -759,13 +759,30 @@ class ORBDaemonController:
 
     @property
     def running(self) -> bool:
-        """True if the daemon process is alive (PID file + kill-0 check)."""
+        """True if the daemon process is alive (PID file + kill-0 check, zombie-safe)."""
         pid_file = self._pid_file()
         if not pid_file.exists():
             return False
         try:
             pid = int(pid_file.read_text().strip())
             os.kill(pid, 0)   # signal 0: probe without sending anything
+            # kill-0 succeeds for zombie processes too — check /proc or ps to exclude zombies
+            try:
+                import subprocess as _sp
+                result = _sp.run(
+                    ["ps", "-p", str(pid), "-o", "stat="],
+                    capture_output=True, text=True, timeout=2,
+                )
+                stat = result.stdout.strip()
+                if stat.startswith("Z"):
+                    # Zombie — treat as dead, clean up PID file
+                    try:
+                        pid_file.unlink()
+                    except Exception:
+                        pass
+                    return False
+            except Exception:
+                pass  # if ps fails, trust kill-0 result
             return True
         except (ValueError, ProcessLookupError, PermissionError, OSError):
             # Process dead or PID stale — remove the file