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

stt/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "ocw-stt"
+version = "0.1.0"
+description = "Local, offline speech-to-text engine for OpenWorker hosts"
+edition = "2021"
+rust-version = "1.77"
+license = "MIT"
+
+[dependencies]
+cpal = "0.15.3"
+serde = { version = "1", features = ["derive"] }
+sha2 = "0.10"
+ureq = "2.12"
+# Keep the v1 engine compatible with macOS releases that predate newer Metal
+# APIs. We can add an opt-in Metal build once the packaged app has a verified
+# minimum macOS target.
+whisper-rs = "0.16"