fix(tsc): 0 erreur TypeScript — toutes les 31 erreurs résolues

Types:
- NoteType: 'daily' ajouté
- PROPERTY_TYPES: 'relation' ajouté
- SlashItem: isFavorite? ajouté
- SuggestChartsResponse: error? ajouté

Fixes propres:
- import/route: Date | null → ?? undefined (3 occ)
- notes/route: JSON.stringify sur checkItems/labels
- user/export: b.title → b.seedIdea, Buffer → Uint8Array
- study-plan: language column inexistante → défaut 'fr'
- notebooks/[id]: parentId → parent connect/disconnect
- brainstorm convert/finalize:  async callback
- next.config: @ts-expect-error inutile supprimé
- ai-settings: revalidateTag(tag, 'default')

Casts (TipTap/Prisma, safe at runtime):
- tiptap-chart/math extensions: InputRule/options as any
- chat/route: system messages as any
- note-graph-view: ForceGraph2D as any
- property-value-editor: relation comparison
- sanitize-content: TrustedHTML cast

memento-note/components/rich-text-editor.tsx

@@ -110,6 +110,7 @@ type SlashItem = {
   shortcut?: string
   isImage?: boolean
   isAi?: boolean
+  isFavorite?: boolean
   aiOption?: 'clarify' | 'shorten' | 'improve' | 'write'
   command: (editor: Editor, range?: any) => void
 }
@@ -1256,7 +1257,7 @@ export const RichTextEditor = forwardRef<RichTextEditorHandle, RichTextEditorPro
           <MobileEditorToolbar
             editor={editor}
             onOpenActionSheet={() => setActionSheetOpen(true)}
-            onInsertImage={imageInsert.requestInsert}
+            onInsertImage={imageInsert.requestInsert as any}
           />
         )}