fix: deep bug hunt II — concurrency, security & optimization (25 files)

Critical: watchdog mutex panic safety, SetGeoAppOverride nil guard,
SSD-only app DB restore fallback.

High: double deploy race (atomic Deploying flag), delete/remove during
deploy guard, ScanStacks overwrite protection, FileBrowser mount mutex,
PushEvent history, PushOnce error handling, DB dump sync+close before
rename, restic retry fresh context, encrypt failure logging, cross-backup
path traversal validation, deepCopyStack completeness.

Security: constant-time API key comparison, login rate limiting (5/min),
git credential masking in logs, storage path prefix traversal fix.

Concurrency: MigrateEncryption lock ordering, SubdomainInUse I/O outside
lock, scheduler late-registered jobs, SQLite WAL verification, metrics
shutdown context, telemetry scan error logging, asset sync lock scope.

Optimization: streaming file copy for DB dumps, restic stats dedup,
atomic infra config copy.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

controller/internal/sync/sync.go

@@ -424,7 +424,7 @@ func (s *Syncer) runGitInDir(dir string, args ...string) error {
 	cmd.Stdout = io.Discard
 	cmd.Stderr = &stderr
 
-	s.logger.Printf("[SYNC] Running: git %s", strings.Join(args, " "))
+	s.logger.Printf("[SYNC] Running: git %s", maskRepoURL(strings.Join(args, " ")))
 
 	if err := cmd.Run(); err != nil {
 		return fmt.Errorf("git %s: %w\nstderr: %s", strings.Join(args, " "), err, stderr.String())