feat(ai): sidebar epuree, suivi visuel des requetes et correctif menu @ (BUG-012, #82)

BUG-012: le menu @ est toujours rendu et _mentionVault() retombe sur le vault de contexte puis le premier vault disponible. #82: suppression des intitules Fournisseur & modele / Fournisseur:, description du contexte General en info-bulle, placeholder retire, bouton Envoyer en emoji, indicateur d'activite (envoi/reception/outils/confirmation/succes/echec), SW_VERSION v5.

frontend/locales/en.json

@@ -142,6 +142,13 @@
   "ai.cap_video": "Video",
   "ai.cap_vision": "Vision capable",
   "ai.commands": "Commands",
+  "ai.activity_sending": "Sending request…",
+  "ai.activity_streaming": "Receiving response…",
+  "ai.activity_tool": "Tool: {name}…",
+  "ai.activity_confirmation": "Waiting for confirmation…",
+  "ai.activity_error": "Request failed",
+  "ai.activity_done": "Done",
+  "ai.composer_label": "Message to the assistant",
   "ai.create_skill": "Create a skill",
   "ai.image": "image",
   "ai.keys": "Stored API keys",
@@ -1712,7 +1719,7 @@
   "bookslm.title": "BooksLM",
   "bookslm.files_indexed": "{count} files indexed",
   "bookslm.chars_loaded": "{chars} chars loaded",
-  "bookslm.placeholder": "Ask a question about these documents...",
+  "bookslm.placeholder": "",
   "bookslm.send": "Send",
   "bookslm.new_conversation": "New conversation",
   "bookslm.export": "Export conversation",

frontend/locales/fr.json

@@ -142,6 +142,13 @@
   "ai.cap_video": "Video",
   "ai.cap_vision": "Vision capable",
   "ai.commands": "Commandes",
+  "ai.activity_sending": "Envoi de la requête…",
+  "ai.activity_streaming": "Réponse en cours…",
+  "ai.activity_tool": "Outil : {name}…",
+  "ai.activity_confirmation": "En attente de confirmation…",
+  "ai.activity_error": "Échec de la requête",
+  "ai.activity_done": "Terminé",
+  "ai.composer_label": "Message à l'assistant",
   "ai.create_skill": "Créer un skill",
   "ai.image": "image",
   "ai.keys": "Clés API enregistrées",
@@ -1712,7 +1719,7 @@
   "bookslm.title": "BooksLM",
   "bookslm.files_indexed": "{count} fichiers indexés",
   "bookslm.chars_loaded": "{chars} caractères chargés",
-  "bookslm.placeholder": "Posez une question sur ces documents...",
+  "bookslm.placeholder": "",
   "bookslm.send": "Envoyer",
   "bookslm.new_conversation": "Nouvelle conversation",
   "bookslm.export": "Exporter la conversation",