fix(pulse-openclaw): update gateway-health test mock for systemctl MainPID

PR #80 changed pgrep to systemctl show --property=MainPID + ps,
but tests still mocked only one execSync call (the ps call).
Now mock systemctl call first, then ps call.

Ref #80

Co-authored-by: 小橘 <xiaoju@shazhou.work>

packages/pulse-openclaw/src/watchers/gateway-health.test.ts

@@ -37,6 +37,7 @@ describe('gatewayHealthWatcher', () => {
       });
 
       mockExecSync
+        .mockReturnValueOnce('12345\n') // systemctl → PID
         .mockReturnValueOnce('1048576\n') // ps → 1048576 KB = 1024 MB
         .mockReturnValueOnce('50\n'); // du
       mockFs.readdirSync.mockReturnValue([]);
@@ -52,7 +53,7 @@ describe('gatewayHealthWatcher', () => {
         fsFn: mockFs as any,
       });
 
-      mockExecSync.mockReturnValueOnce(''); // no process
+      mockExecSync.mockReturnValueOnce('0\n'); // systemctl → MainPID=0 (not running)
       mockFs.readdirSync.mockReturnValue([]);
 
       const result = await watcher.collect();
@@ -158,6 +159,7 @@ describe('gatewayHealthWatcher', () => {
       });
 
       mockExecSync
+        .mockReturnValueOnce('12345\n') // systemctl → PID
         .mockReturnValueOnce('512\n') // ps
         .mockReturnValueOnce('125\t/path\n'); // du → 125 MB