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/notebooks-list.tsx

@@ -234,7 +234,7 @@ export function NotebooksList() {
                       )}
                     >
                       <NotebookIcon className="w-5 h-5 flex-shrink-0" />
-                      <span className="text-sm font-medium tracking-wide truncate flex-1 text-left">{notebook.name}</span>
+                      <span className="text-sm font-medium tracking-wide truncate min-w-0 text-left">{notebook.name}</span>
                       {notebook.notesCount > 0 && (
                         <span className="text-xs text-gray-400 ml-2 flex-shrink-0">({notebook.notesCount})</span>
                       )}