Add manual backup creation and delete buttons to Update Manager (#1255)

* Add manual backup creation and delete buttons to Update Manager

- Add "Create Backup" button in the backups tab for on-demand backups
- Add delete buttons (trash icons) for update logs and backups
- New controller routes with CSRF protection and permission checks
- Use data-turbo-confirm for CSP-safe confirmation dialogs
- Add deleteLog() method to UpdateExecutor with filename validation

* Add Docker backup support: download button, SQLite restore fix, decouple from auto-update

- Decouple backup creation/restore UI from can_auto_update so Docker
  and other non-git installations can use backup features
- Add backup download endpoint for saving backups externally
- Fix SQLite restore to use configured DATABASE_URL path instead of
  hardcoded var/app.db (affects Docker and custom SQLite paths)
- Show Docker-specific warning about var/backups/ not being persisted
- Pass is_docker flag to template via InstallationTypeDetector

* Add tests for backup/update manager improvements

- Controller tests: auth, CSRF validation, 404 for missing backups, restore disabled check
- UpdateExecutor: deleteLog validation, non-existent file, successful deletion
- BackupManager: deleteBackup validation for missing/non-zip files

* Fix test failures: add locale prefix to URLs, correct log directory path

* Fix auth test: expect 401 instead of redirect for HTTP Basic auth

* Improve test coverage for update manager controller

Add happy-path tests for backup creation, deletion, download,
and log deletion with valid CSRF tokens. Also test the locked
state blocking backup creation.

* Fix CSRF tests: initialize session before getting tokens

* Fix CSRF tests: extract tokens from rendered page HTML

* Harden backup security: password confirmation, CSRF, env toggle

Address security review feedback from jbtronics:

- Add IS_AUTHENTICATED_FULLY to all sensitive endpoints (create/delete
  backup, delete log, download backup, start update, restore)
- Change backup download from GET to POST with CSRF token
- Require password confirmation before downloading backups (backups
  contain sensitive data like password hashes and secrets)
- Add DISABLE_BACKUP_DOWNLOAD env var (default: disabled) to control
  whether backup downloads are allowed
- Add password confirmation modal with security warning in template
- Add comprehensive tests: auth checks, env var blocking, POST-only
  enforcement, status/progress endpoint auth

* Fix download modal: use per-backup modals for CSP/Turbo compatibility

- Replace shared modal + inline JS with per-backup modals that have
  filename pre-set in hidden fields (no JavaScript needed)
- Add data-turbo="false" to download forms for native browser handling
- Add data-bs-dismiss="modal" to submit button to auto-close modal
- Add hidden username field for Chrome accessibility best practice
- Fix test: GET on POST-only route returns 404 not 405

* Fixed translation keys

* Fixed text justification in download modal

* Hardenened security of deleteLogEndpoint

* Show whether backup, restores and updates are allowed or disabled by sysadmin on update manager

* Added documentation for update manager related env variables

---------

Co-authored-by: Jan Böhmer <mail@jan-boehmer.de>

docs/configuration.md

@@ -144,6 +144,18 @@ bundled with Part-DB. Set `DATABASE_MYSQL_SSL_VERIFY_CERT` if you want to accept
 * `ALLOW_EMAIL_PW_RESET`: Set this value to true, if you want to allow users to reset their password via an email
   notification. You have to configure the mail provider first before via the MAILER_DSN setting.
 
+### Update manager settings
+* `DISABLE_WEB_UPDATES` (default `1`): Set this to 0 to enable web-based updates. When enabled, you can perform updates
+  via the web interface in the update manager. This is disabled by default for security reasons, as it can be a risk if
+  not used carefully. You can still use the CLI commands to perform updates, even when web updates are disabled.
+* `DISABLE_BACKUP_RESTORE` (default `1`): Set this to 0 to enable backup restore via the web interface. When enabled, you can
+  restore backups via the web interface in the update manager. This is disabled by default for security reasons, as it can
+  be a risk if not used carefully. You can still use the CLI commands to perform backup restores, even when web-based
+  backup restore is disabled.
+* `DISABLE_BACKUP_DOWNLOAD` (default `1`): Set this to 0 to enable backup download via the web interface. When enabled, you can download backups via the web interface
+  in the update manager. This is disabled by default for security reasons, as it can be a risk if not used carefully, as
+  the downloads contain sensitive data like password hashes or secrets.
+
 ### Table related settings
 
 * `TABLE_DEFAULT_PAGE_SIZE`: The default page size for tables. This is the number of rows which are shown per page. Set