fix: fail unsafe lint fixer success states

[chubes4]

Summary

• Treat write-mode formatter failures as hard errors instead of success-shaped warnings, covering both inter-stage and post-write formatting.
• Re-run lint diagnostics after lint fix-only applies changes and fail when findings remain, so lint --fix / refactor --from lint --write cannot report applied success for a still-rejected worktree.
• Add regression coverage for formatter failure and remaining-findings rejection.

Fixes #3938.

Testing

• cargo fmt
• cargo test sources::tests::

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (GPT-5.5)
• Used for: Investigating issue Lint fixer reports applied PHPCBF edits while leaving dirty worktree in rejected formatting state #3938, implementing the failure-state guards, adding regression tests, and running targeted verification; Chris remains responsible for review and final acceptance.

[homeboy-ci]

Homeboy Results — homeboy

Lint

✅ lint — passed

ℹ️ Full options: homeboy docs commands/lint
ℹ️ Save lint baseline: homeboy lint homeboy --baseline
Deep dive: homeboy lint homeboy --changed-since 31a73da

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-homeboy-lint-quality-Linux contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-homeboy-lint-quality-Linux contains exported Homeboy run history for deeper queries.
• Drill-down: download the observation artifact, then run homeboy runs import <dir>, homeboy runs list, and homeboy runs findings <run-id>.
• Artifacts are attached to the workflow run: https://github.com/Extra-Chill/homeboy/actions/runs/27290142979

Test

✅ test — passed

• 4260 passed
• 23 skipped

ℹ️ Set --setting require_phpunit_tests=true when this component is expected to contain PHPUnit tests.
ℹ️ Auto-fix lint issues: homeboy refactor homeboy --from lint --write
ℹ️ Collect coverage: homeboy test homeboy --coverage
ℹ️ Pass args to test runner: homeboy test -- [args]
ℹ️ Full options: homeboy docs commands/test
Deep dive: homeboy test homeboy --changed-since 31a73da

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-homeboy-test-quality-Linux contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-homeboy-test-quality-Linux contains exported Homeboy run history for deeper queries.
• Drill-down: download the observation artifact, then run homeboy runs import <dir>, homeboy runs list, and homeboy runs findings <run-id>.
• Artifacts are attached to the workflow run: https://github.com/Extra-Chill/homeboy/actions/runs/27290142979

Audit

✅ audit — passed

• core_boundary_leak:core-agnostic-source — 3 finding(s)
• structural — 3 finding(s)
• field_patterns — 2 finding(s)
• Runs (Tests) — 1 finding(s)
• intra-method-duplication — 1 finding(s)
• Total: 10 finding(s)

Deep dive: homeboy audit homeboy --changed-since 31a73da

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-homeboy-audit-quality-Linux contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-homeboy-audit-quality-Linux contains exported Homeboy run history for deeper queries.
• Drill-down: download the observation artifact, then run homeboy runs import <dir>, homeboy runs list, and homeboy runs findings <run-id>.
• Artifacts are attached to the workflow run: https://github.com/Extra-Chill/homeboy/actions/runs/27290142979

Tooling versions

• Homeboy CLI: homeboy 0.228.0+e40d06b6
• Extension: rust from https://github.com/Extra-Chill/homeboy-extensions
• Extension revision: 8758c05d
• Action: unknown@unknown