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/unrouted.py

@@ -0,0 +1,67 @@
+"""Unrouted / dead-letter store — a durable record of inbound messages that had nowhere to go and
+of background turns that failed, so neither vanishes silently.
+
+Two producers:
+  - a DM (or any non-channel) inbound message with no designated session to handle it;
+  - a background turn (channel delivery, self-wake) that errored on an ERROR engine event.
+
+JSON-backed and capped (newest kept), mirroring SubscriptionStore's persistence. This is a
+visibility/debugging surface, not a queue — entries are read in the GUI, not redelivered.
+"""
+
+from __future__ import annotations
+
+import json
+import threading
+import time
+from dataclasses import asdict, dataclass, field
+from pathlib import Path
+from typing import Optional
+
+
+@dataclass
+class UnroutedItem:
+    source: str  # message origin / session id (e.g. "slack:D123" or a session id)
+    sender: str  # who sent it ("-" when not applicable, e.g. a turn failure)
+    text: str  # the message (or the failing instruction)
+    reason: str  # why it landed here ("no DM session designated", an error string, …)
+    ts: float = field(default_factory=time.time)
+
+
+class UnroutedStore:
+    def __init__(self, path: Optional[str | Path] = None, *, cap: int = 200) -> None:
+        self.path = Path(path) if path else None
+        self._cap = cap
+        self._lock = threading.Lock()
+        self._items: list[UnroutedItem] = []
+        self._load()
+
+    def _load(self) -> None:
+        if self.path and self.path.is_file():
+            data = json.loads(self.path.read_text(encoding="utf-8"))
+            self._items = [UnroutedItem(**raw) for raw in data.get("items", [])]
+
+    def _save(self) -> None:
+        if not self.path:
+            return
+        self.path.parent.mkdir(parents=True, exist_ok=True)
+        self.path.write_text(
+            json.dumps({"items": [asdict(i) for i in self._items]}, indent=2),
+            encoding="utf-8",
+        )
+
+    def record(self, source: str, sender: str, text: str, reason: str) -> UnroutedItem:
+        item = UnroutedItem(
+            source=source or "?", sender=sender or "-", text=text or "", reason=reason
+        )
+        with self._lock:
+            self._items.append(item)
+            if len(self._items) > self._cap:
+                self._items = self._items[-self._cap :]
+            self._save()
+        return item
+
+    def list(self, n: int = 100) -> list[dict]:
+        """Most-recent-first, for the GUI panel."""
+        items = list(reversed(self._items))[: max(1, n)]
+        return [asdict(i) for i in items]