fix: i18n system overhaul and sidebar UI bugs

- Fix LanguageProvider: add RTL support (ar/fa), translation caching,
  prevent blank flash during load, browser language detection
- Fix detect-user-language: extend whitelist from 5 to all 15 languages
- Remove hardcoded initialLanguage="fr" from auth layout
- Complete fr.json translation (all sections translated from English)
- Add missing admin.ai keys to all 13 non-English locales
- Translate ai.autoLabels, ai.batchOrganization, memoryEcho sections
  for all locales
- Remove duplicate top-level autoLabels/batchOrganization from en.json
- Fix notebook creation: replace window.location.reload() with
  createNotebookOptimistic + router.refresh()
- Fix notebook name truncation in sidebar with min-w-0
- Remove redundant router.refresh() after note creation in page.tsx

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

keep-notes/components/note-actions.tsx

@@ -87,6 +87,21 @@ export function NoteActions({
           </Button>
         </DropdownMenuTrigger>
         <DropdownMenuContent align="end">
+          {/* Pin/Unpin Option */}
+          <DropdownMenuItem onClick={onTogglePin}>
+            {isPinned ? (
+              <>
+                <Pin className="h-4 w-4 mr-2" />
+                {t('notes.unpin')}
+              </>
+            ) : (
+              <>
+                <Pin className="h-4 w-4 mr-2" />
+                {t('notes.pin')}
+              </>
+            )}
+          </DropdownMenuItem>
+
           <DropdownMenuItem onClick={onToggleArchive}>
             {isArchived ? (
               <>