log_parsers: read jest headers with a project name or .mts path

[jayzuccarelli]

With projects, jest prints each project's displayName between the
label and the path (PASS unit src/a.test.js), and its default
testMatch also runs .mts / .cts files. Neither header matched, so
those tests lost their file prefix or were filed under the previous
file. Same-named tests in different files then overwrote each other,
and names changed with jest's file order between the pre and post runs.

Summary

• Skip an optional display name before the path in _JEST_FILE_RE, and
  accept the extensions jest's default testMatch does ([mc]?[jt]sx?),
  in both jest_parser.py and the standalone verifier.
• New tests/test_jest_output.py runs both parsers on plain and colored
  multi-project headers and on .mts / .cts files.
• Extends the long-line stall test with header-shaped noise; a looser
  (?:.*?\s)? version of this regex went quadratic on PASS plus
  whitespace.

Test plan

• pytest tests/test_jest_output.py: 6 fail on main, pass here
• pytest tests/test_jest_output.py tests/test_mocha_output.py tests/test_log_parsers_polyglot.py plus the other parser test files: 152 passed
• ruff check . and ruff format --check .

Out of scope

• _JEST_TARGETABLE_EXT in pr_runtime.py also lacks .mts / .cts;
  that only falls back to running the whole suite.

Prepared with AI assistance (Claude Code); I reviewed the change and ran the tests.