v0.279.0: after_install (decision 45), known default logins on the page, Part D empty-backup alarm, night chain (R-705), R-706

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

controller/internal/web/handler_debug.go

@@ -75,6 +75,9 @@ func (s *Server) handleDebugAPI(w http.ResponseWriter, r *http.Request) {
 	// it. Only the debug route was absent, so this is IMPLEMENTED rather than deleted.
 	case subpath == "backup/crossdrive" && r.Method == http.MethodPost:
 		s.debugRunCrossDrive(w, r)
+	// R-705 (v0.279.0): the night's four legs, in order, now.
+	case subpath == "backup/night-chain" && r.Method == http.MethodPost:
+		s.debugRunNightChain(w, r)
 	// R-397 — the button at debug.html:83 has posted here since it was added and NOTHING answered.
 	// Verified 2026-08-30: this dispatch had no such case, so pressing „Restic integritás" did
 	// nothing at all. Seventh instance of built-but-never-wired in this project; filed as R-400 in its