Work attempt patch follows the user's diff.submodule setting #287

Expected and actual behavior / 实际现象与期望

PATCH_FORMAT_ARGS (server/local_git.py) pins the patch format the Host parses, but not the submodule format. With diff.submodule=log or diff.submodule=diff in the user's Git config, the attempt patch (and collect_diff's patch) changes shape when a submodule pointer moves:

• log: Git writes Submodule vendor abc..def: followed by > commit subject lines. The parser appends each > ... line as a context line to the previous file's last hunk.
• diff: Git writes the submodule's own changes as diff --git a/vendor/lib.txt b/vendor/lib.txt. The canvas lists files inside the submodule as attempt changes, next to a hunk-less vendor entry from changed_files.

Expected: the default Subproject commit <old> / Subproject commit <new> hunk for the submodule path, regardless of user configuration.

Steps to reproduce / 复现步骤

In a workspace with a submodule at vendor:

git config diff.submodule log    # or: diff

Run an attempt that commits inside vendor and edits app.txt in the main repository, then open the attempt diff.

Actual (log): the app.txt hunk ends with an extra context line > library change, and vendor has no hunks.
Actual (diff): an extra vendor/lib.txt entry.
Expected: app.txt with its own hunk and vendor with the Subproject commit hunk.

Relevant environment / 使用环境

Platform-independent; current main (f86c72a). Reproduced with Git 2.43 and 2.54.

Sanitized evidence / 错误信息或截图（请先脱敏）

git diff --submodule=short overrides diff.submodule for one command, like the options already in PATCH_FORMAT_ARGS.

Related issues or fixes / 相关问题或修复

Follow-up to #279 / #284; the submodule configuration was noted as a separate follow-up in the #284 review.