fix(update): host-side watchdog replaces in-container rebuild

Root cause: docker compose down killed the nohup script inside the
container before rebuild could complete — only git pull was visible
(updated VERSION file).

Changes:
- update_host.sh: new host-side watchdog (poll .update_trigger every 3s)
  runs: git pull → docker compose down → build --no-cache app → up -d
  PROJECT_DIR and User are dynamic (set at install time, not hardcoded)
- update_service.py: perform_update() now writes .update_trigger instead
  of running git/docker commands inside the container
- deploy.sh: added install_update_watchdog() + --watchdog CLI option;
  generates /etc/systemd/system/pvemanager-update.service dynamically
  with correct User= and WorkingDirectory= for any install path/user
- .gitignore: ignore .update_trigger and generated systemd/ files
- CHANGELOG, VERSION, WIKI: bump to v1.1.1, document new update flow

.gitignore

@@ -22,6 +22,12 @@ node_modules/
 *.swp
 *.swo
 
+# Update trigger (written by panel, consumed by pvemanager-update.service on host)
+.update_trigger
+
+# Generated systemd files (created by deploy.sh when not root)
+systemd/
+
 # Environment
 .env
 .env.local