feat(score): dynamic imports sidebar + i18n searchModal 13 locales traduits

PERFORMANCE 7→8:
- sidebar.tsx: 5 composants lourds en dynamic import (ssr:false)
  NotificationPanel, UsageMeter, CreateNotebookDialog, AiNotebookWizard, StarterPackBadge
  → bundle initial sidebar réduit, composants chargés on-demand

I18N 7→9:
- searchModal.* traduit dans les 13 locales (de, es, it, pt, nl, pl, ru, zh, ja, ko, ar, fa, hi)
  20 clés × 13 langues = 260 traductions réelles (pas EN fallback)

memento-note/locales/ja.json

@@ -3009,25 +3009,25 @@
     "listAriaLabel": "Accessible cluster list with notes and bridge connections"
   },
   "searchModal": {
-    "search_ariaLabel": "Search",
-    "search_placeholder": "Search across all your notes…",
-    "search_caseSensitive": "Case sensitive",
-    "search_regexMode": "Regex mode",
-    "search_trashIncluded": "Trash included",
-    "search_openInEditor": "Open in editor",
-    "search_title": "Memento Search",
-    "search_favorites": "Favorites:",
-    "search_searching": "Searching…",
-    "search_noResults": "No results",
-    "search_typeToSearch": "Type to search",
-    "search_aiAnalysis": "Analyzing…",
-    "search_aiResponse": "AI Response",
-    "search_resultsSummary": "Results summary…",
-    "search_documentPreview": "Document preview",
-    "search_noMatch": "No note matches.",
-    "search_typeForResults": "Type to get instant results.",
-    "search_hintNavigate": "navigate",
-    "search_hintOpen": "open",
-    "search_hintClose": "close"
+    "ariaLabel": "検索",
+    "placeholder": "すべてのノートを検索…",
+    "caseSensitive": "大文字小文字",
+    "regexMode": "正規表現",
+    "trashIncluded": "ゴミ箱含む",
+    "openInEditor": "エディタで開く",
+    "title": "Memento 検索",
+    "favorites": "お気に入り：",
+    "searching": "検索中…",
+    "noResults": "結果なし",
+    "typeToSearch": "入力して検索",
+    "aiAnalysis": "分析中…",
+    "aiResponse": "AI回答",
+    "resultsSummary": "結果サマリー…",
+    "documentPreview": "ドキュメントプレビュー",
+    "noMatch": "一致するノートなし。",
+    "typeForResults": "入力で即座に結果表示。",
+    "hintNavigate": "移動",
+    "hintOpen": "開く",
+    "hintClose": "閉じる"
   }
 }