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/tiptap-database-block-extension.tsx

@@ -0,0 +1,117 @@
+'use client'
+
+import { Node, mergeAttributes } from '@tiptap/core'
+import { ReactNodeViewRenderer, NodeViewWrapper, type NodeViewProps } from '@tiptap/react'
+import { useCallback } from 'react'
+import type { Editor } from '@tiptap/core'
+import type { Node as PMNode } from '@tiptap/pm/model'
+import { DatabaseBlockEditor } from '@/components/database-block-editor'
+import { NOTE_REQUEST_SAVE_EVENT } from '@/lib/note-change-sync'
+import {
+  createDefaultDatabaseBlockData,
+  parseDatabaseBlockAttrs,
+  serializeDatabaseBlockData,
+  type DatabaseBlockData,
+} from '@/lib/editor/database-block-types'
+
+function DatabaseBlockView({ node, updateAttributes, editor }: NodeViewProps) {
+  const data = parseDatabaseBlockAttrs(node.attrs)
+
+  const requestSave = useCallback(() => {
+    const hostNoteId = editor.storage.liveBlock?.hostNoteId
+    if (hostNoteId) {
+      window.dispatchEvent(new CustomEvent(NOTE_REQUEST_SAVE_EVENT, {
+        detail: { noteId: hostNoteId, reason: 'database-block-mutation' },
+      }))
+    }
+  }, [editor])
+
+  const handleChange = useCallback((next: DatabaseBlockData) => {
+    updateAttributes(serializeDatabaseBlockData(next))
+    requestSave()
+  }, [requestSave, updateAttributes])
+
+  return (
+    <NodeViewWrapper className="database-block-wrapper" data-drag-handle contentEditable={false}>
+      <DatabaseBlockEditor data={data} onChange={handleChange} />
+    </NodeViewWrapper>
+  )
+}
+
+export const DatabaseBlockExtension = Node.create({
+  name: 'databaseBlock',
+  group: 'block',
+  atom: true,
+  draggable: true,
+  selectable: true,
+
+  addAttributes() {
+    return {
+      dbId: {
+        default: '',
+        parseHTML: (element) => element.getAttribute('data-db-id') || '',
+        renderHTML: (attributes) => (attributes.dbId ? { 'data-db-id': attributes.dbId } : {}),
+      },
+      dbView: {
+        default: 'table',
+        parseHTML: (element) => element.getAttribute('data-db-view') || 'table',
+        renderHTML: (attributes) => ({ 'data-db-view': attributes.dbView || 'table' }),
+      },
+      dbAuthorsJson: {
+        default: '[]',
+        parseHTML: (element) => element.getAttribute('data-db-authors') || '[]',
+        renderHTML: (attributes) => ({ 'data-db-authors': attributes.dbAuthorsJson || '[]' }),
+      },
+      dbBooksJson: {
+        default: '[]',
+        parseHTML: (element) => element.getAttribute('data-db-books') || '[]',
+        renderHTML: (attributes) => ({ 'data-db-books': attributes.dbBooksJson || '[]' }),
+      },
+    }
+  },
+
+  parseHTML() {
+    return [{ tag: 'div[data-database-block]' }]
+  },
+
+  renderHTML({ HTMLAttributes }) {
+    return ['div', mergeAttributes(HTMLAttributes, { 'data-database-block': 'true' })]
+  },
+
+  addNodeView() {
+    return ReactNodeViewRenderer(DatabaseBlockView)
+  },
+})
+
+export function insertDatabaseBlockAtSelection(editor: Editor): boolean {
+  const type = editor.schema.nodes.databaseBlock
+  if (!type) return false
+
+  const attrs = serializeDatabaseBlockData(createDefaultDatabaseBlockData())
+  const { empty, $from } = editor.state.selection
+  const parent = $from.parent
+
+  if (empty && parent.type.name === 'paragraph' && parent.content.size === 0) {
+    const pos = $from.before()
+    return editor
+      .chain()
+      .focus()
+      .command(({ tr, dispatch }) => {
+        tr.replaceWith(pos, pos + parent.nodeSize, type.create(attrs))
+        if (dispatch) dispatch(tr)
+        return true
+      })
+      .run()
+  }
+
+  return editor.chain().focus().insertContent({ type: 'databaseBlock', attrs }).run()
+}
+
+export function replaceBlockWithDatabase(editor: Editor, blockPos: number, blockNode: PMNode): void {
+  const type = editor.schema.nodes.databaseBlock
+  if (!type || blockPos < 0 || !blockNode) return
+  const attrs = serializeDatabaseBlockData(createDefaultDatabaseBlockData())
+  const dbNode = type.create(attrs)
+  editor.view.dispatch(editor.state.tr.replaceWith(blockPos, blockPos + blockNode.nodeSize, dbNode))
+  editor.commands.focus()
+}