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/notify/notifier.go

@@ -210,11 +210,17 @@ func (n *Notifier) PushEvent(eventType, severity, message string, details interf
 					n.logger.Printf("[DEBUG] PushEvent: %s pushed OK (HTTP %d)", eventType, resp.StatusCode)
 				}
 				n.logger.Printf("[INFO] Event pushed: %s (%s) — %s", eventType, severity, message)
+				n.recordHistory(eventType, severity, message, resp.StatusCode, "")
 				return
 			}
 			lastErr = fmt.Errorf("HTTP %d", resp.StatusCode)
 		}
 		n.logger.Printf("[WARN] Event push failed after 3 attempts (%s/%s): %v", eventType, severity, lastErr)
+		errMsg := ""
+		if lastErr != nil {
+			errMsg = lastErr.Error()
+		}
+		n.recordHistory(eventType, severity, message, 0, errMsg)
 	}()
 }