refactor(webui): separate backup component into sub-system folders

backup/ held 15 loose .js plus css/html at the component root. Split into
per-tab sub-systems mirroring the admin/apps layout:

  backup/core/{js,css,html}/   schema, base BackupPage, fetch-client,
                               cron-schedule, backup.css, backup-content.html
  backup/dashboard/js/         backup-dashboard
  backup/snapshots/js/         backup-snapshots, backup-snapshot-actions
  backup/locations/js/         backup-locations, backup-location-fields,
                               backup-location-modal, backup-ssh-key
  backup/migrate/js/           backup-migrate
  backup/configuration/js/     backup-configuration, backup-retention-presets,
                               backup-engine-details

Updated the scripts[] array + loadFragment in index.js, the backup.css href in
index.html, and the handleBackup() fallback paths in spa.js. No behaviour
change — files moved verbatim (prototype-augment clusters), all 17 referenced
paths verified to resolve, node --check clean.

Signed-off-by: librelad <librelad@digitalangels.vip>

containers/libreportal/frontend/components/backup/index.js

@@ -13,29 +13,30 @@ LP.features.register({
   id: 'backup',
   routes: ['/backup', '/backup*'],
   // Controllers the feature needs; lazy-loaded on first mount (idempotent).
+  // Controllers, organised by sub-system (tabs). core/ first: schema + base
+  // class + the shared data/cron, then each tab's prototype-augment clusters.
   scripts: [
-    '/components/backup/js/backup-schema.js',
-    '/components/backup/js/backup-page.js',          // base: class + constructor + init/switchTab/render
-    // prototype-augment clusters (load after the base, order among them is free):
-    '/components/backup/js/backup-fetch-client.js',
-    '/components/backup/js/backup-dashboard.js',
-    '/components/backup/js/backup-snapshots.js',
-    '/components/backup/js/backup-locations.js',
-    '/components/backup/js/backup-location-fields.js',
-    '/components/backup/js/backup-ssh-key.js',
-    '/components/backup/js/backup-retention-presets.js',
-    '/components/backup/js/backup-configuration.js',
-    '/components/backup/js/backup-engine-details.js',
-    '/components/backup/js/backup-location-modal.js',
-    '/components/backup/js/backup-snapshot-actions.js',
-    '/components/backup/js/backup-migrate.js',
-    '/components/backup/js/backup-cron-schedule.js',
+    '/components/backup/core/js/backup-schema.js',
+    '/components/backup/core/js/backup-page.js',          // base: class + constructor + init/switchTab/render
+    '/components/backup/core/js/backup-fetch-client.js',
+    '/components/backup/core/js/backup-cron-schedule.js',
+    '/components/backup/dashboard/js/backup-dashboard.js',
+    '/components/backup/snapshots/js/backup-snapshots.js',
+    '/components/backup/snapshots/js/backup-snapshot-actions.js',
+    '/components/backup/locations/js/backup-locations.js',
+    '/components/backup/locations/js/backup-location-fields.js',
+    '/components/backup/locations/js/backup-location-modal.js',
+    '/components/backup/locations/js/backup-ssh-key.js',
+    '/components/backup/migrate/js/backup-migrate.js',
+    '/components/backup/configuration/js/backup-configuration.js',
+    '/components/backup/configuration/js/backup-retention-presets.js',
+    '/components/backup/configuration/js/backup-engine-details.js',
     '/core/lib/backup-app-card.js',
   ],
 
   async mount(ctx) {
     await ctx.loadScripts(this.scripts);
-    const html = await ctx.loadFragment('/components/backup/html/backup-content.html');
+    const html = await ctx.loadFragment('/components/backup/core/html/backup-content.html');
     ctx.setContent(html, 'Backups');
     if (typeof BackupPage === 'undefined') {
       throw new Error('BackupPage controller failed to load');

containers/libreportal/frontend/core/kernel/spa.js

@@ -370,10 +370,10 @@ class LibrePortalSPAClean {
       // backup-page.js + backup-app-card.js are loaded on first navigation.
       // loadScript is idempotent — subsequent /backup navigations are no-ops.
       await Promise.all([
-        this.loadScript('/components/backup/js/backup-page.js'),
+        this.loadScript('/components/backup/core/js/backup-page.js'),
         this.loadScript('/core/lib/backup-app-card.js')
       ]);
-      const html = await this.fetchContent('/components/backup/html/backup-content.html');
+      const html = await this.fetchContent('/components/backup/core/html/backup-content.html');
       this.loadContent(html, 'Backups');
       if (typeof BackupPage !== 'undefined') {
         window.backupPage = new BackupPage();

containers/libreportal/frontend/index.html

@@ -18,7 +18,7 @@
   <link rel="stylesheet" href="/core/css/style.css">
   <link rel="stylesheet" href="/components/admin/config/css/ip-whitelist.css">
   <link rel="stylesheet" href="/components/apps/port-manager/css/port-manager.css">
-  <link rel="stylesheet" href="/components/backup/css/backup.css">
+  <link rel="stylesheet" href="/components/backup/core/css/backup.css">
   <link rel="stylesheet" href="/components/admin/ssh/css/ssh.css">
   <link rel="stylesheet" href="/components/admin/core/css/admin.css">
   <link rel="stylesheet" href="/components/apps/services/css/services.css">