feat(git): follow repository style when generating commit and PR text

Commit generation now samples the last 10 commit subjects and instructs the
model to match their language, prefix convention, and length, falling back to
Conventional Commits only when the history shows no consistent style.

PR generation probes the conventional pull request template locations and
reuses the repository's own sections and checklists as the body structure when
one is found.

Claude-Session: https://claude.ai/code/session_01NzK8hD1hFHHHwv2FgZJwC2

CHANGELOG.md

@@ -5,6 +5,8 @@ All notable changes to this project will be documented in this file.
 ## [Unreleased]
 
 - **Dictation:** speech is now transcribed after you stop talking, instead of being re-guessed word by word while you speak. The offline models OpenChamber runs are built to read a whole utterance at once, so the running transcript was consistently worse than the final one. While recording, the composer shows a live waveform of your voice and a timer, then Transcribing while the text is produced. Long recordings are split at pauses in your speech rather than on a timer, so a three-minute dictation still returns a few seconds after you stop, and words are no longer cut in half at the split.
+- Git: generated commit messages now follow the style of the repository's recent commits, including their language, so repositories that commit in Korean or without a `feat:`-style prefix get messages that match instead of English Conventional Commits.
+- Git: generating a pull request description now picks up the repository's own PR template when it has one, so the draft comes back in your project's sections and checklists instead of the built-in Summary/Why/Testing layout.
 - Chat: if OpenCode restarts while a response is still running, the chat now stops with an interrupted state and a notification to continue instead of hanging silently (thanks to @sum117).
 
 ## [1.19.0] - 2026-08-19