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/agents/base.py

@@ -0,0 +1,53 @@
+"""Agent — a top-level surface (Code / Chat / Cowork).
+
+An agent owns its system prompt + base toolset + whether it needs a workspace. Distinct
+from a Skill: skills are Anthropic-format, loadable capabilities that ANY agent can pull
+in (see coworker.skills).
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+from pathlib import Path
+from typing import Any, Callable, Optional
+
+from ..tools.todo import TodoList
+
+
+@dataclass
+class AgentContext:
+    workspace: Optional[Path] = None
+    executor: Optional[Any] = None
+    todo: Optional[TodoList] = None
+    # Shared, mutable list of RootDir the session may touch (primary scratch + added folders).
+    # When None, tools fall back to the single `workspace` root. Held by reference so runtime
+    # add/remove of folders is seen by the file tools built from it.
+    roots: Optional[list] = None
+
+
+@dataclass
+class Agent:
+    name: str
+    title: str
+    system_prompt: str
+    tool_factory: Optional[Callable[[AgentContext], list]] = None
+    # Traits that replace the old per-agent-name branching in build_engine / manager.
+    # requires_folder: the session cannot start without a user-picked primary folder
+    # (composer + engine gate; everything else starts on a scratch dir). subagents:
+    # read-only explorer fan-out. scheduling: scheduled tasks + self-wake. messaging:
+    # exposes send_message. connectors: loads the integration toolset — True = every
+    # connected connector (general builtins only), a tuple = allowlist (session gets
+    # declared ∩ connected; OPE-93), False = none. Defaults keep non-persona callers
+    # behaving as before. (The old family/needs_workspace/workspace trio collapsed into
+    # these — see ocw-context/docs/workspace-scratch-design.md.)
+    requires_folder: bool = False
+    subagents: bool = False
+    scheduling: bool = False
+    messaging: bool = False
+    connectors: bool | tuple[str, ...] = False
+    # Team identity: "lead" | "worker" | None (solo-only). Gates the board/journal
+    # toolsets and staffing eligibility — solo personas are never team-staffable.
+    team: Optional[str] = None
+
+    def build_tools(self, context: AgentContext) -> list:
+        return list(self.tool_factory(context)) if self.tool_factory else []