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/web/storage_handlers.go

@@ -952,7 +952,7 @@ func (s *Server) storageAttachBrowseHandler(w http.ResponseWriter, r *http.Reque
 
 	// Security: validate path is under the raw mount staging area
 	cleanPath := filepath.Clean(browsePath)
-	if !strings.HasPrefix(cleanPath, storage.RawMountBase) {
+	if cleanPath != storage.RawMountBase && !strings.HasPrefix(cleanPath, storage.RawMountBase+"/") {
 		jsonError(w, "Érvénytelen útvonal", http.StatusBadRequest)
 		return
 	}