feat(sync): scaffold monorepo, extract docmost-client, add Phase-0 harness + read-only pull

Lock the access-layer decision (REST only) and start implementation per SPEC.

- monorepo (npm workspaces): packages/docmost-client = DocmostClient + lib/*
  copied 1:1 from docmost-mcp/src (backport target), plus bannered sync methods
  (listTrash, restorePage, listAllSpacePages, exportPageBody, listRecentSince /
  collectRecentSince cursor scan)
- engine stays the root app per AGENTS.md (src/, test/, build/, data/, settings.ts);
  add roundtrip.ts (SPEC §11 idempotency harness), pull.ts (SPEC §6 read-only
  Docmost->FS mirror), sanitize.ts (SPEC §12 filenames, path-traversal-safe)
- Dockerfile builds the workspace lib before the app; vitest gates CI
- exportPageBody never touches /comments (SPEC §3); serializeDocmostMarkdownBody
  emits meta + body only
- SPEC: resolve access-layer (REST), reflect root-engine layout + REST pagination
- tests: sanitize (incl. dot-traversal), collectRecentSince (cutoff/dedup/cap),
  stripBlockIds, markdown round-trip byte-stability

Note: raw ProseMirror round-trip is byte-stable in Markdown but not yet attribute-
idempotent (SPEC §11 Задача №0, before Phase 2).

packages/docmost-client/package.json

@@ -0,0 +1,44 @@
+{
+  "name": "docmost-client",
+  "version": "0.1.0",
+  "private": true,
+  "type": "module",
+  "main": "dist/index.js",
+  "types": "dist/index.d.ts",
+  "exports": {
+    ".": {
+      "types": "./dist/index.d.ts",
+      "import": "./dist/index.js"
+    }
+  },
+  "scripts": {
+    "build": "tsc -p tsconfig.json"
+  },
+  "dependencies": {
+    "@fellow/prosemirror-recreate-transform": "^1.2.3",
+    "@hocuspocus/provider": "^3.4.4",
+    "@hocuspocus/transformer": "^3.4.4",
+    "@tiptap/core": "^3.18.0",
+    "@tiptap/extension-highlight": "^3.26.1",
+    "@tiptap/extension-image": "^3.18.0",
+    "@tiptap/extension-subscript": "^3.26.1",
+    "@tiptap/extension-superscript": "^3.26.1",
+    "@tiptap/extension-task-item": "^3.26.1",
+    "@tiptap/extension-task-list": "^3.26.1",
+    "@tiptap/html": "^3.18.0",
+    "@tiptap/pm": "^3.18.0",
+    "@tiptap/starter-kit": "^3.18.0",
+    "axios": "^1.6.0",
+    "form-data": "^4.0.0",
+    "jsdom": "^27.4.0",
+    "marked": "^17.0.1",
+    "ws": "^8.19.0",
+    "yjs": "^13.6.29"
+  },
+  "devDependencies": {
+    "@types/jsdom": "^27.0.0",
+    "@types/node": "^20.0.0",
+    "@types/ws": "^8.5.10",
+    "typescript": "^5.0.0"
+  }
+}