fix: quick deploy duplicate detection, logout UX, backup toggle, CSP, SSE guard, and migration

- Detect existing projects with same image on quick deploy; show conflict dialog with options
- Move logout button to sidebar header as icon-only
- Replace backup checkbox with ToggleSwitch component
- Allow unsafe-inline in CSP script-src for SvelteKit hydration
- Guard SSE connection behind isAuthenticated() check
- Add notification_url ALTER TABLE migration for existing databases
- Restore RegisterPersistentLogger on event bus

internal/store/store.go

@@ -99,6 +99,7 @@ func (s *Store) runMigrations() error {
 		`ALTER TABLE settings ADD COLUMN backup_enabled INTEGER NOT NULL DEFAULT 0`,
 		`ALTER TABLE settings ADD COLUMN backup_interval_hours INTEGER NOT NULL DEFAULT 24`,
 		`ALTER TABLE settings ADD COLUMN backup_retention_count INTEGER NOT NULL DEFAULT 10`,
+		`ALTER TABLE stages ADD COLUMN notification_url TEXT NOT NULL DEFAULT ''`,
 	}
 
 	for _, m := range migrations {