feat: comprehensive debug logging across all controller modules

Add detailed [DEBUG] logging to every controller module when
logging.level is set to "debug". Each module with stateful debug
uses SetDebug(bool) wired from main.go. Covers stacks, backup,
cloudflare, integrations, system, monitor, settings, scheduler,
web handlers, storage, metrics, API, selfupdate, and assets.

Also includes the app export/import (.fab bundles) feature from
v0.32.0 and its debug page integration.

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

controller/internal/api/router.go

@@ -59,6 +59,19 @@ type Router struct {
 
 	// App-to-app integration manager (nil if not configured)
 	integrationMgr *integrations.Manager
+
+	debug bool
+}
+
+// SetDebug enables or disables debug logging for API routing.
+func (r *Router) SetDebug(on bool) {
+	r.debug = on
+}
+
+func (r *Router) dbg(format string, args ...interface{}) {
+	if r.debug {
+		r.logger.Printf("[DEBUG] [api] "+format, args...)
+	}
 }
 
 // SetAssetsSyncer sets the Hub asset syncer for on-demand sync triggers.
@@ -92,6 +105,8 @@ func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 	path := strings.TrimPrefix(req.URL.Path, "/api")
 	path = strings.TrimSuffix(path, "/")
 
+	r.dbg("%s %s (path=%s)", req.Method, req.URL.Path, path)
+
 	switch {
 	// GET /api/stacks
 	case path == "/stacks" && req.Method == http.MethodGet:
@@ -282,6 +297,7 @@ func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 		r.geoRemoveAppOverride(w, req, extractName(path, "/geo/override"))
 
 	default:
+		r.dbg("no matching route: %s %s", req.Method, path)
 		writeJSON(w, http.StatusNotFound, apiResponse{OK: false, Error: "endpoint not found"})
 	}
 }
@@ -340,6 +356,7 @@ func (r *Router) getDeployFields(w http.ResponseWriter, _ *http.Request, name st
 func (r *Router) deployStack(w http.ResponseWriter, req *http.Request, name string) {
 	limitBody(w, req)
 	r.logger.Printf("[API] Deploy requested for stack: %s", name)
+	r.dbg("deployStack: name=%s contentLength=%d", name, req.ContentLength)
 
 	var body struct {
 		Values map[string]string `json:"values"`
@@ -396,6 +413,7 @@ func (r *Router) deployStack(w http.ResponseWriter, req *http.Request, name stri
 
 func (r *Router) actionStack(w http.ResponseWriter, action, name string) {
 	r.logger.Printf("[API] %s requested for stack: %s", action, name)
+	r.dbg("actionStack: action=%s name=%s", action, name)
 
 	// Protected stacks only allow restart — block all other actions
 	if r.cfg.IsProtectedStack(name) && action != "restart" {
@@ -587,6 +605,7 @@ func (r *Router) removeStack(w http.ResponseWriter, req *http.Request, name stri
 	}
 	limitBody(w, req)
 	r.logger.Printf("[API] Remove requested for stack: %s", name)
+	r.dbg("removeStack: name=%s", name)
 
 	var body struct {
 		RemoveHDDData bool `json:"remove_hdd_data"`
@@ -596,6 +615,7 @@ func (r *Router) removeStack(w http.ResponseWriter, req *http.Request, name stri
 		body.RemoveHDDData = false
 		body.RemoveBackups = false
 	}
+	r.dbg("removeStack: name=%s removeHDDData=%v removeBackups=%v", name, body.RemoveHDDData, body.RemoveBackups)
 
 	// Compute backup paths to remove if requested
 	var backupPaths []string
@@ -750,12 +770,14 @@ func (r *Router) backupStatus(w http.ResponseWriter, _ *http.Request) {
 }
 
 func (r *Router) triggerBackup(w http.ResponseWriter, _ *http.Request) {
+	r.dbg("triggerBackup: backupMgr=%v", r.backupMgr != nil)
 	if r.backupMgr == nil {
 		writeJSON(w, http.StatusBadRequest, apiResponse{OK: false, Error: "Backup not configured"})
 		return
 	}
 
 	if r.backupMgr.IsRunning() {
+		r.dbg("triggerBackup: backup already running, rejecting")
 		writeJSON(w, http.StatusConflict, apiResponse{OK: false, Error: "Mentés már folyamatban"})
 		return
 	}
@@ -1130,6 +1152,7 @@ func (r *Router) selfupdateTrigger(w http.ResponseWriter, _ *http.Request) {
 // --- Config apply handler ---
 
 func (r *Router) configApply(w http.ResponseWriter, req *http.Request) {
+	r.dbg("configApply: contentLength=%d remoteAddr=%s", req.ContentLength, req.RemoteAddr)
 	// Read YAML body (limit to 1MB)
 	body, err := io.ReadAll(io.LimitReader(req.Body, 1<<20))
 	if err != nil {