refactor: simplification

[rustatian]

Reason for This PR

Reduce the code and dependencies needed to maintain the worker pool.

Description of Changes

• Remove unused PHP fixtures and duplicate test suites. Reuse the slow payload worker and remove four Composer requirements.
• Simplify worker cleanup, restart jitter, and library calls. Remove unused fields and the always-nil error result from WorkerWatcher.Watch.
• Combine the test and coverage commands. Use the built-in Go cache in CI.

License Acceptance

By submitting this pull request, I confirm that my contribution is made under the terms of the MIT license.

PR Checklist

• All commits in this PR are signed (git commit -s -S).
• The reason for this PR is clearly provided.
• The description of changes is clear and encompassing.
• Any required documentation changes are included in this PR.
• User-facing API changes are described above; this repository has no CHANGELOG.md.
• All added or changed functionality is tested.

[Copilot]

Copilot review overview

🟢 Approval recommended

The functional simplifications preserve existing behavior, and removed fixtures and tests have retained equivalents or no remaining references.

Review effort: Balanced
Findings: None

What changed in this PR

Simplifies worker-pool maintenance by removing redundant fixtures/tests, eliminating unused abstractions, and consolidating CI testing and caching.

Changes:

• Simplifies worker initialization, jitter calculation, watcher cleanup, and IPC factories.
• Removes obsolete PHP fixtures, dependencies, and duplicate Go test suites.
• Consolidates Go test coverage and adopts setup-go caching.

File	Description
worker/​worker.go	Uses io.CopyBuffer directly.
worker/​options.go	Simplifies restart jitter generation.
worker_watcher/​worker_watcher.go	Simplifies watcher API and cleanup paths.
tests/​worker-slow-dyn.php	Removes redundant slow worker.
tests/​stream_worker.php	Removes unused stream fixture.
tests/​src/​Workflow/​SagaWorkflow.php	Removes unused workflow fixture.
tests/​src/​Client/​StartNewWorkflow.php	Removes unused client fixture.
tests/​src/​Activity/​SimpleActivity.php	Removes unused activity fixture.
tests/​socket_test_script.sh	Removes obsolete socket script.
tests/​slow-pid.php	Removes unused PID fixture.
tests/​sample.txt	Removes unused sample data.
tests/​raw-error.php	Removes unused error fixture.
tests/​psr-worker.php	Removes obsolete PSR worker.
tests/​psr-worker-slow.php	Removes obsolete slow PSR worker.
tests/​psr-worker-post.php	Removes obsolete POST worker.
tests/​psr-worker-bench.php	Removes obsolete benchmark worker.
tests/​pipes_test_script.sh	Removes obsolete pipe script.
tests/​metrics-issue-571.php	Removes unused metrics fixture.
tests/​issue659.php	Removes obsolete regression fixture.
tests/​http/​user-agent.php	Removes unused HTTP fixture.
tests/​http/​upload.php	Removes unused upload fixture.
tests/​http/​stuck.php	Removes unused stuck-worker fixture.
tests/​http/​slow-client.php	Removes obsolete HTTP client.
tests/​http/​server.php	Removes unused server fixture.
tests/​http/​request-uri.php	Removes unused URI fixture.
tests/​http/​push.php	Removes unused push fixture.
tests/​http/​pid.php	Removes unused PID fixture.
tests/​http/​payload.php	Removes unused payload fixture.
tests/​http/​memleak.php	Removes unused memory fixture.
tests/​http/​ip.php	Removes unused address fixture.
tests/​http/​headers.php	Removes unused headers fixture.
tests/​http/​header.php	Removes unused header fixture.
tests/​http/​error2.php	Removes unused exit fixture.
tests/​http/​error.php	Removes unused error fixture.
tests/​http/​env.php	Removes unused environment fixture.
tests/​http/​echoerr.php	Removes unused stderr fixture.
tests/​http/​echoDelay.php	Removes unused delayed echo fixture.
tests/​http/​echo.php	Removes unused echo fixture.
tests/​http/​data.php	Removes unused form-data fixture.
tests/​http/​cookie.php	Removes unused cookie fixture.
tests/​http/​client.php	Removes obsolete HTTP harness.
tests/​gzip-large-file.txt	Removes unused test data.
tests/​composer.json	Drops dependencies needed only by removed fixtures.
pool/​static_pool/​supervisor_test.go	Removes a redundant supervisor test.
pool/​static_pool/​pool.go	Removes unused fields and nil-only errors.
pool/​static_pool/​pool_test.go	Reuses the shared slow worker fixture.
pool/​static_pool/​dyn_allocator_test.go	Reuses the shared slow worker fixture.
Makefile	Consolidates test and coverage commands.
ipc/​socket/​socket.go	Stores relays directly.
ipc/​socket/​socket_test.go	Defines the shared discard logger.
ipc/​socket/​socket_spawn_test.go	Removes duplicate socket tests.
ipc/​pipe/​pipe.go	Removes the unused logger field.
ipc/​pipe/​pipe_test.go	Consolidates tests and strengthens timeout setup.
ipc/​pipe/​pipe_spawn_test.go	Removes duplicate pipe tests.
.github/​workflows/​tests.yml	Uses setup-go caching and earlier checkout.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.13%. Comparing base (23f9030) to head (fef82e8).

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #70      +/-   ##
==========================================
- Coverage   77.54%   77.13%   -0.41%     
==========================================
  Files          19       20       +1     
  Lines        1171     1159      -12     
==========================================
- Hits          908      894      -14     
- Misses        263      265       +2     

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