fix(#2767): pass paths via --files to gsd-sdk query commit + lint guard (#2781)

* fix(#2767): pass paths via --files to gsd-sdk query commit + lint guard

Workflows, agents, commands, and references passed file paths positionally
to `gsd-sdk query commit`, which silently appended them to the commit
subject and triggered the `.planning/` wholesale-stage fallback in
sdk/src/query/commit.ts:136. Regression of #733/#798.

Inserted `--files` before the path list at every site (81 invocations
across 50 files). Added tests/bug-2767-gsd-sdk-commit-files-flag.test.cjs
as a permanent lint that scans every shipped .md file and asserts each
`gsd-sdk query commit[-to-subrepo]` invocation either uses `--files` or
carries no path arguments.

Closes #2767

* test(#2767): replace source-grep with behavioral SDK test

The original test walked every shipped .md file and regex-tokenized
`gsd-sdk query commit` invocations to assert `--files` was present.
CONTRIBUTING.md prohibits this source-grep pattern.

Rewrite as behavioral SDK tests against `sdk/dist/cli.js` over a real
tmp git project (createTempGitProject helper). Cover both the
well-formed (`--files <paths>`) form — clean subject, exactly-staged
files, .planning/ left untouched — and the buggy positional form,
asserting the documented misbehavior (paths leak into subject + the
`.planning/` wholesale-stage fallback at commit.ts:136). Also asserts
`commit-to-subrepo` rejects when `--files` is omitted (commit.ts:258).

The doc-lint is retained as a supplementary defense-in-depth guard
since agent-prompt markdown invocations cannot be exercised end-to-end
— but it is no longer the primary contract.

* docs(#2767): correct contradictory --files guidance in zh-CN/en docs + fix test docstring

get-shit-done/workflows/map-codebase.md

@@ -378,7 +378,7 @@ Continue to commit_codebase_map.
 Commit the codebase map:
 
 ```bash
-gsd-sdk query commit "docs: map existing codebase" .planning/codebase/*.md
+gsd-sdk query commit "docs: map existing codebase" --files .planning/codebase/*.md
 ```
 
 Continue to offer_next.