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/locales/en.json

@@ -291,34 +291,6 @@
       "regenerating": "Regenerating summary..."
     }
   },
-  "batchOrganization": {
-    "error": "Failed to create organization plan",
-    "noNotesSelected": "No notes selected",
-    "title": "Organize with AI",
-    "description": "AI will analyze your notes and suggest organizing them into notebooks.",
-    "analyzing": "Analyzing your notes...",
-    "notesToOrganize": "{count} notes to organize",
-    "selected": "{count} selected",
-    "noNotebooks": "No notebooks available. Create notebooks first to organize your notes.",
-    "noSuggestions": "AI could not find a good way to organize these notes.",
-    "confidence": "confidence",
-    "unorganized": "{count} notes couldn't be categorized and will stay in General Notes.",
-    "applying": "Applying...",
-    "apply": "Apply ({count})"
-  },
-  "autoLabels": {
-    "error": "Failed to fetch label suggestions",
-    "noLabelsSelected": "No labels selected",
-    "created": "{count} labels created successfully",
-    "analyzing": "Analyzing your notes...",
-    "title": "New Label Suggestions",
-    "description": "I've detected recurring themes in \"{notebookName}\" ({totalNotes} notes). Create labels for them?",
-    "note": "note",
-    "notes": "notes",
-    "typeContent": "Type content to get label suggestions...",
-    "createNewLabel": "Create this new label and add it",
-    "new": "(new)"
-  },
   "titleSuggestions": {
     "available": "Title suggestions",
     "title": "AI suggestions",