feat: editor improvements and architectural grid prototype

Multiple feature additions and improvements across the application:

- NextGen Editor: drag handles, smart paste, block actions
- Structured views: Kanban and table layouts for notes
- Architectural Grid: new brainstorming/agent interface prototype
- Flashcards: SM-2 revision algorithm with AI generation
- MCP server: robustness improvements
- Graph/PDF chat: fix click propagation and copy behavior
- Various UI/UX enhancements and bug fixes

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

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

@@ -1,8 +1,9 @@
 'use client'
 
-import { NoteEditorProvider, useNoteEditorContext } from './note-editor-context'
+import { NoteEditorProvider } from './note-editor-context'
 import { NoteEditorFullPage } from './note-editor-full-page'
 import { NoteEditorDialog } from './note-editor-dialog'
+import { NoteEditorPeekHost } from './note-editor-peek-host'
 import { Note } from '@/lib/types'
 
 interface NoteEditorProps {
@@ -16,11 +17,13 @@ interface NoteEditorProps {
 export function NoteEditor({ note, readOnly, onClose, fullPage = false, onNoteSaved }: NoteEditorProps) {
   return (
     <NoteEditorProvider note={note} readOnly={readOnly} fullPage={fullPage} onNoteSaved={onNoteSaved}>
-      {fullPage ? (
-        <NoteEditorFullPage onClose={onClose} />
-      ) : (
-        <NoteEditorDialog onClose={onClose} />
-      )}
+      <NoteEditorPeekHost noteId={note.id} fullPage={fullPage}>
+        {fullPage ? (
+          <NoteEditorFullPage onClose={onClose} />
+        ) : (
+          <NoteEditorDialog onClose={onClose} />
+        )}
+      </NoteEditorPeekHost>
     </NoteEditorProvider>
   )
 }
@@ -35,4 +38,4 @@ export { NoteEditorProvider } from './note-editor-context'
 export { NoteTitleBlock } from './note-title-block'
 export { NoteContentArea } from './note-content-area'
 export { NoteMetadataSection } from './note-metadata-section'
-export { NoteEditorToolbar } from './note-editor-toolbar'
+export { NoteEditorToolbar } from './note-editor-toolbar'