[hi-ogawa]

• stacked on feat: expose per-retry/repeat attempt result #11232
• related Custom reporters can't access per-attempt details for retries #10303

TODO: review

TestCase.attempts() from #11232 fills in while a test runs, but no reporter hook fires when a single run finishes, and the existing test-retried event never reaches a reporter hook. This PR adds a test-attempt-finished runner event that is sent after every retry and repeat run. It carries that run's attempt and calls a new onTestCaseAttempt(testCase, attempt) reporter hook. test-retried is kept but marked deprecated.

onTestCaseReady    |flaky|
  onHookStart      |flaky| [beforeEach]
  onHookEnd        |flaky| [beforeEach]
onTestCaseAttempt  |flaky| [repeat 0, retry 0, failed]
  onHookStart      |flaky| [beforeEach]
  onHookEnd        |flaky| [beforeEach]
onTestCaseAttempt  |flaky| [repeat 0, retry 1, passed]
  ...
onTestCaseAttempt  |flaky| [repeat 1, retry 1, passed]
onTestCaseResult   |flaky|

Because the event carries its own attempt, the hook always gets the right run even though task updates are batched. Tests configured with retry or repeats also send the batch immediately after each attempt, so testCase.attempts() inside the hook ends with that attempt. Tests that run only once keep the normal 100ms batching, so they don't pay for an extra message.

path	how attempts are delivered
node pools	test-attempt-finished event with { attempt } data
browser mode	same event, forwarded unchanged by the existing onTaskUpdate RPC
--merge-reports	convertTasksToEvents replays one event per saved attempt before test-finished

🤖 Generated with Claude Code

[hi-ogawa]

This appears less immediate need than #11232 so closing. Feel free to take over if any interest or create a new issue request if there's a need.