feat: 新增小宇宙播客转文字渠道 (#124)

* feat: add Xiaoyuzhou podcast transcription channel

- New channel: 小宇宙播客 (xiaoyuzhoufm.com) → full text transcript
- Uses Groq Whisper API (free, no credit card needed)
- Auto-downloads audio, converts to low-bitrate MP3, splits by 25MB limit
- Supports any length podcast with automatic chunking
- Script installed to ~/.agent-reach/tools/xiaoyuzhou/transcribe.sh
- User just needs: agent-reach configure groq-key gsk_xxxxx
- Updated README (CN/EN), install.md, pyproject.toml

* docs: clarify Xiaoyuzhou setup — free key, limitations, step-by-step

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Co-authored-by: Panniantong <panniantong@users.noreply.github.com>

pyproject.toml

@@ -67,6 +67,7 @@ packages = ["agent_reach"]
 [tool.hatch.build.targets.wheel.force-include]
 "agent_reach/guides" = "agent_reach/guides"
 "agent_reach/skill" = "agent_reach/skill"
+"agent_reach/scripts" = "agent_reach/scripts"
 
 [tool.ruff]
 target-version = "py310"