fix(ci): stop releasable-commit-types flagging release-please's own release commit

[JSONbored]

Closes #10286. Unblocks #10283, whose drift-checks-history is red for exactly this reason.

What

releasable-commit-types:check fails on every release-please release PR, flagging release-please's own release commit:

  54e2df7e chore(release): cut ui-kit v1.7.0
      packages/loopover-ui-kit/package.json

publishedSourcePrefixes includes <pkg>/package.json, and a release commit's whole job is to write the new version into that file under chore(release): — a hidden type. The match is structural, so it fires on every release PR, and the message's claim is backwards: that commit is the one that performs the release, not one that will never reach npm. A maintainer also cannot fix it by rewording, because release-please generates the commit.

The file's own isPublishedFile note already makes the argument: "a guard that fires on the ordinary case is a guard that gets disabled."

Why keyed on the diff, not the subject

Matching chore(release): in the subject would be simpler and weaker — a hand-written commit borrowing that subject while editing a dependency range or an exports map still strands a real change. So isVersionOnlyManifestBump exempts a path only when its diff's sole changed lines are the "version" field. Consequences, all tested:

• A commit left with no other published-source path is release-please's own → not stranded.
• A mixed commit still reports its remaining paths (the version bump drops out, the source file stays).
• An empty diff proves nothing and stays flagged — which keeps the default accessor's behaviour, and every existing caller, unchanged.

Verified against the live failure

Ran the fixed code over #10283's real commit range (origin/main...release-please--branches--main--components--ui-kit), with real git show diffs:

commits checked: 2
  4bcced8a0 chore(release): sync package-lock.json
  54e2df7e6 chore(release): cut ui-kit v1.7.0

RESULT: none stranded -- check PASSES

Tests

33 pass. New coverage: the release commit is allowed; a chore(release): that also edits a dependency range is still flagged; a mixed commit reports only its non-version paths; no-diff still flags; plus five direct isVersionOnlyManifestBump cases including diff-header lines and a non-manifest file. The original #9937 recharts regression test is untouched and still passes.

[superagent-security]

Superagent didn't find any vulnerabilities or security issues in this PR.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.31%. Comparing base (7f27a0f) to head (321ef8f).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #10287   +/-   ##
=======================================
  Coverage   92.31%   92.31%           
=======================================
  Files         939      939           
  Lines      114816   114816           
  Branches    27729    27729           
=======================================
  Hits       105989   105989           
  Misses       7527     7527           
  Partials     1300     1300           

Flag	Coverage Δ
backend	95.71% <ø> (ø)

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