feat(sidebar+assistant): filtre Recents/Sauvegardes (#99), pastille Deep Research (#100) et icone du bouton + (BUG-049)

frontend/style.css

@@ -9676,6 +9676,7 @@ body.bookslm-resizing { cursor: ew-resize; user-select: none; }
 .bookslm-chip-remove:hover { color: #f87171; }
 .bookslm-chip-thumb { width: 18px; height: 18px; object-fit: cover; border-radius: 4px; }
 .bookslm-chip-skill { border-color: var(--accent); }
+.bookslm-chip-deep-research { border-color: var(--accent); }
 /* Composer menus (`/` commands and `@` mentions). */
 .bookslm-menu-layer { position: relative; }
 .bookslm-command-menu, .bookslm-mention-menu { position: absolute; left: 12px; right: 12px; bottom: 4px;
@@ -9696,10 +9697,10 @@ body.bookslm-resizing { cursor: ew-resize; user-select: none; }
   white-space: nowrap; }
 .bookslm-menu-empty { padding: 10px; font-size: 12px; color: var(--text-secondary); text-align: center; }
 /* Image attach button. */
-.bookslm-btn-plus { display: flex; align-items: center; justify-content: center; flex-shrink: 0;
+.bookslm-input-area button.bookslm-btn-plus { display: flex; align-items: center; justify-content: center; flex-shrink: 0;
   background: none; border: 1px solid var(--border); color: var(--text-secondary); cursor: pointer;
   border-radius: 50%; width: 32px; height: 32px; padding: 0; }
-.bookslm-btn-plus:hover { color: var(--accent); border-color: var(--accent); }
+.bookslm-input-area button.bookslm-btn-plus:hover { color: var(--accent); border-color: var(--accent); }
 .bookslm-file-input { display: none; }
 .bookslm-files-input { display: none; }
 /* Extensible "+" panel (#97). */