v0.12.7: mandatory HDD backup, pre-dump, restore for all apps

Fix 1: HDD data backup is now mandatory for all deployed apps.
resolveAppBackupPaths() iterates ListDeployedStacks() directly — no
longer reads GetAppBackupMap() or checks the Enabled flag. DiscoverAppData()
drops backupPrefs parameter; BackupEnabled is set from HasHDDData.
Five dead settings methods removed: IsAppBackupEnabled, SetAppBackup,
GetAppBackupMap, SetAppBackupBulk, GetAppBackupPrefs.

Fix 2: Cross-drive backup now triggers a fresh DB dump (DumpStackDB)
before running. DBDumper interface added to crossdrive.go; Manager
implements it; SetDBDumper wired in main.go. Non-fatal — proceeds with
user data backup even if DB dump fails.

Fix 3: Restore dropdown shows ALL deployed apps (not just HDD+enabled).
restore.go rewritten: always restores config+DB, adds user data if hasHDD.
UI shows restore type banner (full / config+DB / config only) with
color-coded styling. Snapshot API clarified for non-HDD apps.

Fix 4: "Docker kötetek" → "Konfiguráció" — named volumes are not in
the restic backup paths; compose files + app.yaml are what's backed up.

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

controller/internal/api/router.go

@@ -461,8 +461,11 @@ func (r *Router) backupSnapshots(w http.ResponseWriter, req *http.Request) {
 	if stackName := req.URL.Query().Get("stack"); stackName != "" {
 		mounts := r.backupMgr.GetStackHDDMounts(stackName)
 		if len(mounts) > 0 {
+			// App has HDD data — filter to snapshots containing those paths
 			snapshots = filterSnapshotsByPaths(snapshots, mounts)
 		}
+		// Apps without HDD mounts: return all snapshots (they all contain
+		// the stacks dir + DB dumps which cover this app's config and database)
 	}
 
 	if snapshots == nil {