feat(notes): liens internes, onglet Réseau, living blocks et consentement IA

Rend les liens entre notes visibles et persistants (sync NoteLink au save, auto-save, graphe réseau rafraîchi), ajoute living blocks, Memory Echo, recherche globale, consentement IA explicite et consolide les prototypes design en architectural-grid.

Co-authored-by: Cursor <cursoragent@cursor.com>

memento-note/context/search-modal-context.tsx

@@ -0,0 +1,44 @@
+'use client'
+
+import { createContext, useContext, useState, useEffect, type ReactNode } from 'react'
+import { SearchModal } from '@/components/search-modal'
+
+interface SearchModalContextValue {
+  open: () => void
+  close: () => void
+}
+
+const SearchModalContext = createContext<SearchModalContextValue>({
+  open: () => {},
+  close: () => {},
+})
+
+export function useSearchModal() {
+  return useContext(SearchModalContext)
+}
+
+export function SearchModalProvider({ children }: { children: ReactNode }) {
+  const [isOpen, setIsOpen] = useState(false)
+
+  const open = () => setIsOpen(true)
+  const close = () => setIsOpen(false)
+
+  // Global keyboard shortcut: Ctrl+K or Cmd+K
+  useEffect(() => {
+    const handleKeyDown = (e: KeyboardEvent) => {
+      if ((e.ctrlKey || e.metaKey) && e.key === 'k') {
+        e.preventDefault()
+        setIsOpen(prev => !prev)
+      }
+    }
+    window.addEventListener('keydown', handleKeyDown)
+    return () => window.removeEventListener('keydown', handleKeyDown)
+  }, [])
+
+  return (
+    <SearchModalContext.Provider value={{ open, close }}>
+      {children}
+      <SearchModal isOpen={isOpen} onClose={close} />
+    </SearchModalContext.Provider>
+  )
+}