A test pins what a park reason says about each try: the files each red head changed since the one before #6873

triesChanged in src/crew/tries.ts writes the "try N: files" lines a park reason carries, so a planner can see whether the tries kept circling the same files. No test imports it.

Done:

• [ ] test/crew-tries.test.ts, on a real repository with a pull: three failed check runs on three heads give try 1 (files since the base), try 2 and try 3 (each only since the head before it).
• [ ] A green run, a run before since, a repeated head and a non-oid head are skipped. A head that changed nothing says "no files changed".
• [ ] More files than FILES_PER_TRY end in "(+N more)". A long line is cut to LINE_MAX with an ellipsis. Only the last TRIES_TOLD lines are returned.
• [ ] A file name with a newline or markup comes back as the name git gave, and the lines are text, never HTML.

This adds a test file only; change the code only where the test finds a hole, and say so in the pull. It touches no api.ts, MCP tool or docs/MCP.md, so it waits on none of the pulls there.

Before pushing: bun x tsc --noEmit and the test you add. Tests pass now in and never read the wall clock.