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/ja.json

@@ -63,7 +63,13 @@
       "tagsGenerationProvider": "タグ生成プロバイダー",
       "title": "AI設定",
       "updateFailed": "AI設定の更新に失敗しました",
-      "updateSuccess": "AI設定が正常に更新されました"
+      "updateSuccess": "AI設定が正常に更新されました",
+      "bestValue": "最もコスパが良い",
+      "bestQuality": "最高品質",
+      "providerOllamaOption": "🦙 Ollama (Local & Free)",
+      "providerOpenAIOption": "🤖 OpenAI (GPT-5, GPT-4)",
+      "providerCustomOption": "🔧 Custom OpenAI-Compatible",
+      "saved": "(保存済み)"
     },
     "aiTest": {
       "description": "タグ生成とセマンティック検索埋め込みのAIプロバイダーをテストします",
@@ -153,34 +159,36 @@
     "analyzing": "AI分析中...",
     "assistant": "AIアシスタント",
     "autoLabels": {
-      "analyzing": "ラベル提案のためにノートを分析中...",
+      "analyzing": "ノートを分析中...",
       "create": "作成",
-      "createNewLabel": "Create this new label and add it",
-      "created": "{count} labels created successfully",
+      "createNewLabel": "この新しいラベルを作成して追加",
+      "created": "{count} 個のラベルを作成しました",
       "creating": "ラベルを作成中...",
-      "description": "I've detected recurring themes in \"{notebookName}\" ({totalNotes} notes). Create labels for them?",
-      "error": "Failed to fetch label suggestions",
-      "new": "(新規)",
-      "noLabelsSelected": "No labels selected",
-      "note": "note",
-      "notes": "notes",
-      "title": "ラベルの提案",
-      "typeContent": "Type content to get label suggestions..."
+      "description": "\"{notebookName}\"（{totalNotes} 件のノート）で繰り返し出てくるテーマを検出しました。ラベルを作成しますか？",
+      "error": "ラベル候補の取得に失敗しました",
+      "new": "（新規）",
+      "noLabelsSelected": "ラベルが選択されていません",
+      "note": "件",
+      "notes": "件",
+      "title": "新しいラベル候補",
+      "typeContent": "ラベル候補を取得するにはコンテンツを入力...",
+      "notesCount": "{count} 件",
+      "typeForSuggestions": "ラベル候補を取得するにはコンテンツを入力..."
     },
     "batchOrganization": {
-      "analyzing": "Analyzing your notes...",
-      "apply": "Apply",
-      "applyFailed": "Failed to apply organization plan",
-      "applying": "Applying...",
-      "description": "AIがノートを分析し、ノートブックに整理することを提案します。",
-      "error": "Failed to create organization plan",
-      "noNotebooks": "No notebooks available. Create notebooks first to organize your notes.",
-      "noNotesSelected": "No notes selected",
-      "noSuggestions": "AI could not find a good way to organize these notes.",
-      "selectAllIn": "Select all notes in {notebook}",
-      "selectNote": "Select note: {title}",
-      "success": "{count} notes moved successfully",
-      "title": "Organize with AI"
+      "analyzing": "ノートを分析中...",
+      "apply": "適用",
+      "applyFailed": "整理プランの適用に失敗しました",
+      "applying": "適用中...",
+      "description": "AI がノートを分析し、ノートブックに整理する方法を提案します。",
+      "error": "整理プランの作成に失敗しました",
+      "noNotebooks": "利用可能なノートブックがありません。先にノートブックを作成してください。",
+      "noNotesSelected": "ノートが選択されていません",
+      "noSuggestions": "AI はこれらのノートを整理する良い方法を見つけられませんでした。",
+      "selectAllIn": "{notebook} のすべてのノートを選択",
+      "selectNote": "ノートを選択：{title}",
+      "success": "{count} 件のノートを移動しました",
+      "title": "AI で整理"
     },
     "clarify": "明確にする",
     "clickToAddTag": "クリックしてこのタグを追加",
@@ -192,8 +200,8 @@
     "improveStyle": "スタイルを改善",
     "languageDetected": "検出された言語",
     "notebookSummary": {
-      "regenerate": "概要を再生成",
-      "regenerating": "概要を再生成中..."
+      "regenerate": "要約を再生成",
+      "regenerating": "要約を再生成中..."
     },
     "original": "元のテキスト",
     "poweredByAI": "AI powered",