feat(assistant): #94-#97 historique permanent, sidebar IA, panneau + et bouton rond

frontend/locales/en.json

@@ -1829,6 +1829,28 @@
   "bookslm.untitled": "Untitled conversation",
   "bookslm.no_vault": "No active vault to open this link",
   "bookslm.copied_name": "Name copied: {name}",
+  "bookslm.add_options": "Add options",
+  "bookslm.ext_files": "Upload files",
+  "bookslm.ext_files_hint": "Add files to the conversation context",
+  "bookslm.ext_image_hint": "Attach an image for vision-capable models",
+  "bookslm.ext_contexts": "Add contexts",
+  "bookslm.ext_contexts_hint": "Attach files or directories with the @ command",
+  "bookslm.ext_skills": "Add skills",
+  "bookslm.ext_skills_hint": "Select an active skill",
+  "bookslm.ext_deep_research": "Deep Research",
+  "bookslm.ext_deep_research_hint": "Multi-step in-depth research",
+  "bookslm.ext_web": "Internet search",
+  "bookslm.ext_web_hint": "Coming soon",
+  "bookslm.ext_canva": "Canva",
+  "bookslm.ext_canva_hint": "Coming soon",
+  "bookslm.coming_soon": "Feature coming soon",
+  "bookslm.soon": "Soon",
+  "bookslm.ext_more_coming": "More options coming…",
+  "bookslm.deep_research_prompt": "Perform an in-depth analysis of the request by breaking it into steps, searching for relevant information in the vault, cross-referencing them, and producing a structured summary with sources.",
+  "bookslm.deep_research_started": "Deep research started — enable Agent mode to use the tools.",
+  "bookslm.mode_general": "General",
+  "bookslm.mode_directory": "Directory",
+  "bookslm.mode_documents": "Documents",
   "palette.bookslm_open": "BooksLM: Open for current directory",
   "palette.bookslm_open_desc": "Opens the AI assistant for the current context (open documents or general)",
   "palette.bookslm_new": "BooksLM: New conversation",