feat: hierarchical notebook system - trash, selectors, breadcrumb, sidebar tree

- Schema: soft delete with trashedAt on Notebook model
- API: PATCH/GET notebooks support trashedAt filtering with cascade
- Sidebar: recursive tree rendering with collapse/expand, visual guides, hover actions
- HierarchicalNotebookSelector: portal-based dropdown with search, breadcrumbs, dropUp support
- AI chat: context selector with Toutes mes notes + notebook selector
- Agent detail: flat selects replaced with HierarchicalNotebookSelector
- Breadcrumb: notebook path display on home page
- Trash view: card grid with countdown, restore/permanent delete
- CSS: design tokens (ink, paper, blueprint, concrete, etc.)
- Types: parentId, trashedAt added to Notebook interface

memento-note/components/note-editor/note-editor-context.tsx

@@ -822,7 +822,7 @@ export function NoteEditorProvider({ note, readOnly = false, fullPage = false, o
     fullPage,
     state,
     actions,
-    notebooks: notebooks.map(nb => ({ id: nb.id, name: nb.name })),
+    notebooks: notebooks.map(nb => ({ id: nb.id, name: nb.name, parentId: nb.parentId, trashedAt: nb.trashedAt })),
     globalLabels,
     fileInputRef,
     textareaRef,