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/lib/ai/services/chart-suggestion.service.ts

@@ -58,10 +58,10 @@ function getCached(key: string): SuggestChartsResponse | null {
 function setCached(key: string, data: SuggestChartsResponse): void {
   cache.set(key, { data, timestamp: Date.now() })
   // Limit cache size to 50 entries
-  if (cache.size > 50) {
-    const firstKey = cache.keys().next().value
-    cache.delete(firstKey)
-  }
+    if (cache.size > 50) {
+      const firstKey = cache.keys().next().value
+      cache.delete(firstKey || '')
+    }
 }
 
 /**

memento-note/lib/sanitize-content.ts

@@ -20,7 +20,7 @@ const SVG_SANITIZE_CONFIG = {
 
 export function sanitizeIllustrationSvg(svg: string): string {
   if (!svg) return ''
-  return DOMPurify.sanitize(svg, SVG_SANITIZE_CONFIG)
+  return DOMPurify.sanitize(svg, SVG_SANITIZE_CONFIG as any) as unknown as string
 }
 
 export function sanitizeRichHtml(html: string): string {

memento-note/lib/structured-views/types.ts

@@ -5,6 +5,7 @@ export const PROPERTY_TYPES = [
   'select',
   'multiselect',
   'checkbox',
+  'relation',
 ] as const
 
 export type PropertyType = (typeof PROPERTY_TYPES)[number]

memento-note/lib/types.ts

@@ -48,7 +48,7 @@ export interface LinkMetadata {
   siteName?: string;
 }
 
-export type NoteType = 'text' | 'markdown' | 'richtext' | 'checklist'
+export type NoteType = 'text' | 'markdown' | 'richtext' | 'checklist' | 'daily'
 
 export interface Note {
   id: string;