Feature request: configurable language for GitHub comments

[cwbcheng]

Summary

All comments PatchDeck posts to GitHub (status messages, follow-up replies, agent thread replies) are hard-coded in English. For teams that collaborate in another language — e.g. Chinese — every comment appears in English unless the source is forked and modified.

Use case

• A Chinese-speaking team uses PatchDeck to babysit PRs.
• The agent replies to review threads and posts follow-ups; both the fixed templates (STATUS_MESSAGES, buildFeedbackFollowUpBody) and the agent prompt instruct English-only wording.
• Forking and editing the templates works, but it diverges from upstream and is hard to maintain.

Suggested approach

A commentLanguage (or locale) config option that:

1. Selects the language for the fixed templates (STATUS_MESSAGES, buildFeedbackFollowUpBody, "Responding to…" references). A small dictionary keyed by language is enough.
2. Appends a language instruction to the agent prompt so model-generated thread replies match (e.g. "write every GitHub comment, thread reply, and summary in Simplified Chinese").
3. Keeps English as the default, so existing behavior is unchanged.

APP_STATUS_COMMENT_PATTERN in server/github.ts already needs to recognize both English and Chinese status markers for status-reply recovery; making the language configurable means the pattern should be derived from the selected language's markers.

Notes

• Default should remain English for backward compatibility.
• The agent prompt change is the more impactful part: model-generated replies follow whatever the prompt says, so the fixed templates and the prompt must stay in sync.