feat: filtre de recherche dans la sidebar Historique IA (#98) + menus '@' et '/' depuis le menu '+' (BUG-048)

frontend/locales/en.json

@@ -1544,6 +1544,7 @@
   "sidebar.expand_collapse": "Expand/Collapse",
   "sidebar.file_icons": "Icons",
   "sidebar.filter_instant": "Instant search",
+  "sidebar.filter_ai": "Filter AI history...",
   "sidebar.filter_path": "Path filters",
   "sidebar.filter_placeholder": "Filter files...",
   "sidebar.filter_results_grouped": "Grouped results",
@@ -1826,6 +1827,7 @@
   "bookslm.session_history": "Session history",
   "bookslm.session_delete": "Delete session",
   "bookslm.history_empty": "No saved session",
+  "bookslm.history_no_match": "No conversation matches the search",
   "bookslm.untitled": "Untitled conversation",
   "bookslm.no_vault": "No active vault to open this link",
   "bookslm.copied_name": "Name copied: {name}",