Add Docker update support via Watchtower integration

[Sebbeben]

Summary

Extends the Update Manager to support Docker-based installations by integrating with Watchtower, a popular container update tool.

• WatchtowerClient service — communicates with Watchtower's HTTP API to check status and trigger updates
• Docker update progress page — Stimulus-based polling UI that survives container restarts, with progress indicators and timeout handling
• Health endpoint (/update-manager/health) — unauthenticated JSON endpoint for post-restart detection (session is lost when container restarts)
• Docker-specific UI — hides Git-only fields (branch, commit, local changes) for Docker installs, shows Watchtower connection status
• Pre-update backup — creates database backup before triggering Watchtower
• CSP fix — replaces javascript:history.back() with proper navigation in error template

How it works

1. User clicks "Update to latest version" on the Update Manager page
2. Part-DB creates a database backup
3. Part-DB calls Watchtower's HTTP API to trigger an update
4. User is redirected to a progress page that polls the health endpoint
5. When the container restarts with the new image, the health endpoint responds and the UI shows success

Configuration

Docker users add a Watchtower sidecar to their docker-compose.yml:

watchtower:
  image: containrrr/watchtower
  volumes:
    - /var/run/docker.sock:/var/run/docker.sock
  environment:
    - WATCHTOWER_HTTP_API_UPDATE=true
    - WATCHTOWER_HTTP_API_TOKEN=your-secret-token
    - WATCHTOWER_LABEL_ENABLE=true
  ports:
    - "8080:8080"

And set environment variables for Part-DB:

WATCHTOWER_API_URL=http://watchtower:8080
WATCHTOWER_API_TOKEN=your-secret-token

If Watchtower is not configured, the Update Manager gracefully shows an informational message explaining how to enable Docker updates.

Files changed

File	Purpose
src/Services/System/WatchtowerClient.php	New — Watchtower HTTP API client
src/Controller/UpdateManagerController.php	Docker update actions + health endpoint
src/Services/System/UpdateChecker.php	Watchtower status in update info
src/Services/System/UpdateExecutor.php	Docker update validation
src/Services/System/InstallationType.php	Docker supports auto-update
src/EventSubscriber/MaintenanceModeSubscriber.php	Whitelist health endpoint
assets/controllers/docker_update_progress_controller.js	New — Stimulus polling controller
templates/admin/update_manager/docker_progress.html.twig	New — Progress page template
templates/admin/update_manager/index.html.twig	Docker-specific UI sections
templates/bundles/TwigBundle/Exception/error.html.twig	CSP fix for back link
translations/messages.en.xlf	Translation keys for Docker update UI

Test plan

• PHPStan passes (verified, 0 errors)
• Tested on Docker installation (Orange Pi ARM64) with Watchtower sidecar
• Verified update progress UI survives container restart
• Verified graceful degradation when Watchtower is not installed
• Verified health endpoint is accessible without authentication
• Verified CSRF protection on all mutating endpoints

Screenshots

Update Manager - Docker Installation

Update in Progress

Update Complete

note: this is when i was developing and thats why it says updating from v2.9.0 -> v2.9.0

[codecov]

Codecov Report

❌ Patch coverage is 44.89796% with 54 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.39%. Comparing base (4206b70) to head (2626478).

Files with missing lines	Patch %	Lines
src/Controller/UpdateManagerController.php	0.00%	38 Missing ⚠️
src/Services/System/UpdateExecutor.php	10.00%	9 Missing ⚠️
src/Services/System/UpdateChecker.php	60.00%	4 Missing ⚠️
src/Services/System/InstallationType.php	0.00%	2 Missing ⚠️
src/EventSubscriber/MaintenanceModeSubscriber.php	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #1330      +/-   ##
============================================
- Coverage     56.45%   56.39%   -0.06%     
- Complexity     8323     8351      +28     
============================================
  Files           611      612       +1     
  Lines         26731    26824      +93     
============================================
+ Hits          15091    15128      +37     
- Misses        11640    11696      +56     

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