feat: OpenMesh 基础平台与 MD/PDF 转换技能

- 后端: coworker 智能体框架, WS API, 文件上传, 附件处理
- 前端: Open WebUI, 文件全量走 upload API (含 MD/TXT/JSON 等文本类)
- 技能: md-to-office (pandoc + wkhtmltopdf)
- 修复: 上传文件路径丢失, Agent 搜索浪费, 输出文件跑到 uploads/
- 打包: PyInstaller one-dir, 预打包 pandoc/wkhtmltopdf/chromium

coworker/personas/__init__.py

@@ -0,0 +1,22 @@
+"""Personas — specialized coworkers as declarative, skill-shaped bundles.
+
+A persona is a manifest (YAML frontmatter + a markdown body that is the system prompt) that
+composes vetted catalog capabilities, a family/workspace shape, and lifecycle metadata. The
+built-in surfaces (Code, Cowork, Chat, Ops) are themselves manifests — the same format third
+parties use. See `platform/docs/PERSONAS.md`.
+"""
+
+from __future__ import annotations
+
+from .manifest import PersonaManifest, ManifestError, parse_manifest, load_manifest_file
+from .registry import PersonaRegistry, PersonaState, DEFAULT_PERSONA_ID
+
+__all__ = [
+    "PersonaManifest",
+    "ManifestError",
+    "parse_manifest",
+    "load_manifest_file",
+    "PersonaRegistry",
+    "PersonaState",
+    "DEFAULT_PERSONA_ID",
+]