0.14.0: multi-folder media drawer

- Clipart store holds an array of root folders instead of a single
  handle, plus an activeHandleIndex for the in-folder view. Getters:
  activeHandle, inOverview, hasAnyFolder, canGoBack, folderName.
- Actions: addFolder (appends a root), enterFolder, exitFolder,
  removeFolder. Single-folder installs auto-drill into the sole root
  and behave exactly like the pre-refactor drawer; adding a 2nd+
  folder pops back to the root overview.
- IDB persistence migrated from the 'clipartDir' single-handle key to
  a 'clipartDirs' array. Legacy records are migrated on first load.
  saveClipartFolders unwraps Pinia proxies (toRaw per element) so
  IDB's structured clone accepts the payload.
- ClipartItem union gained a 'folder' kind so root tiles render as
  first-class media items. listClipart emits nested directories too,
  but the drawer keeps drill-down one level deep for now.
- ClipartDrawer header: three equally-sized .header-btn chips —
  back (only when canGoBack), refresh (when viewing a folder), and a
  new `+` (when any folder is attached). No more big 'Choose folder'
  button — empty state is a centred 96px dashed + with a wrapped hint.
- Folder tiles carry a hover `×` to remove a root from the library.
- DocumentSettings media tab lists all configured folders with a per-
  folder remove action; primary button is now 'Add folder'.
- Pinia store now calls acceptHMRUpdate so Vite HMR actually swaps
  the store definition between reloads instead of leaving the first-
  load state shape behind.
- Tests: store actions (addFolder / enterFolder / exitFolder / remove
  / IDB round-trip), drawer UI (centred + empty state, overview with
  folder tiles + click-to-enter, back visibility, single-root hides
  back, header + button triggers addFolder). Tests isolated with
  try/finally so a failing store assertion can't leak error state
  into subsequent drawer tests.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/i18n/messages.ts

@@ -438,7 +438,7 @@ export const en = {
     open: 'Open media',
     close: 'Close media',
     refresh: 'Reload folder',
-    empty: 'Choose a folder with images and audio to populate the library.',
+    empty: 'Add a folder with images and audio to populate the library.',
     noFiles: 'No images or audio files in this folder.',
     loading: 'Loading…',
     unsupported: 'Your browser does not support folder access. Try Chrome or Edge.',
@@ -446,8 +446,17 @@ export const en = {
     clearFolder: 'Clear',
     folderLabel: 'Folder',
     noFolder: 'No folder selected',
+    addFolder: 'Add folder',
+    addFolderTooltip: 'Add another media folder',
+    backToIndex: 'Back to folder index',
+    removeFolder: 'Remove folder from library',
+    removeFolderDialog: {
+      title: 'Remove folder from library?',
+      message: '"{name}" will no longer show up in the Media drawer. The files themselves stay untouched on disk.',
+      confirm: 'Remove',
+    },
     settingsHint:
-      'Point to a local folder with your images and audio files. The app remembers the folder; permissions may be re-asked after browser restart.',
+      'Add one or more local folders with your images and audio files. The app remembers them; permissions may be re-asked after browser restart.',
   },
 
   documentDrawer: {
@@ -1206,7 +1215,7 @@ export const de: DeepPartial<Messages> = {
     open: 'Medien öffnen',
     close: 'Medien schließen',
     refresh: 'Ordner neu laden',
-    empty: 'Wähle einen Ordner mit Bildern und Audiodateien, um die Bibliothek zu füllen.',
+    empty: 'Füge einen Ordner mit Bildern und Audiodateien hinzu, um die Bibliothek zu füllen.',
     noFiles: 'In diesem Ordner gibt es keine Bilder oder Audiodateien.',
     loading: 'Lädt…',
     unsupported:
@@ -1215,8 +1224,17 @@ export const de: DeepPartial<Messages> = {
     clearFolder: 'Leeren',
     folderLabel: 'Ordner',
     noFolder: 'Kein Ordner ausgewählt',
+    addFolder: 'Ordner hinzufügen',
+    addFolderTooltip: 'Weiteren Medien-Ordner hinzufügen',
+    backToIndex: 'Zur Ordnerübersicht',
+    removeFolder: 'Ordner aus der Bibliothek entfernen',
+    removeFolderDialog: {
+      title: 'Ordner entfernen?',
+      message: '„{name}" erscheint nicht mehr im Medien-Drawer. Die Dateien auf der Festplatte bleiben unangetastet.',
+      confirm: 'Entfernen',
+    },
     settingsHint:
-      'Verweise auf einen lokalen Ordner mit Bildern und Audio. Die App merkt sich den Ordner. Nach einem Browser-Neustart kann die Berechtigung erneut abgefragt werden.',
+      'Binde einen oder mehrere lokale Ordner mit Bildern und Audio an. Die App merkt sich die Auswahl. Nach einem Browser-Neustart kann die Berechtigung erneut abgefragt werden.',
   },
   documentDrawer: {
     open: 'Dokument-Einstellungen öffnen',