Fixes three test failures that were blocking release workflow:
1. TestApplyDockerReportGeneratesUniqueIDsForCollidingHosts:
- Initialize dockerTokenBindings and dockerMetadataStore in test helper
- These maps were nil causing panic on first access
2. TestSendGroupedAppriseHTTP & TestSendTestNotificationAppriseHTTP:
- Configure allowlist to permit localhost (127.0.0.1) for test servers
- SSRF protection was blocking httptest.NewServer() URLs
- Tests need to allowlist the test server IP to bypass security checks
Related to workflow fix in 5fa78c3e3.
- Add support for testing Apprise notifications via /api/notifications/test endpoint
- Users can now test their Apprise configuration (both CLI and HTTP modes) using method="apprise"
- Added comprehensive unit tests for both CLI and HTTP modes
- Tests verify correct behavior when Apprise is enabled/disabled
- Tests validate that notifications are properly sent through Apprise channels
Related to #584
