feat(rag): harden post-LightRAG runtime

Retire legacy OCR/media/evidence fallbacks, add local-folder event bus and Page Aggregate guards, and archive completed design checklists.

Validation: cargo test -p mnote-web -- --test-threads=1; cargo test --workspace -- --test-threads=1; git diff --check; codegraph sync .; codegraph_status.

rust/crates/mnote-web/browser/local-upload-runtime.js

@@ -413,23 +413,8 @@ async function uploadLocalFolderAsset(file, plan, context) {
 }
 
 async function uploadMediaAsset(file, plan, context) {
-  var form = new FormData();
-  form.append('file', file);
-  form.append('workspaceId', plan && plan.workspaceId || '');
-  form.append('documentId', plan && plan.targetDocumentId || '');
-  if (plan && plan.targetMindmapId) form.append('mindmapId', plan.targetMindmapId);
-  var response = await fetchWithTimeout('/api/media/upload', {
-    method: 'POST',
-    credentials: 'include',
-    body: form
-  }, Number(context && context.timeoutMs) || 15000, '上传');
-  var payload = await response.json().catch(function() { return null; });
-  if (!response.ok || !payload || !payload.asset) {
-    throw new Error(payload && payload.error ? payload.error : '上传失败');
-  }
-  return {
-    asset: payload.asset
-  };
+  document.documentElement.setAttribute('data-mnote-media-upload-retired', 'true');
+  throw new Error('旧 Convex Files 上传链已退役；local-first 附件请使用本地文件夹上传目标。');
 }
 
 async function insertUploadedAssetIntoEditor(asset, targetRoot, deps) {