Ship Laravel Zero 12 support (PR #43 - unblock CI) #52

Context

PR #43 adds Laravel Zero 12 support (constraint change: `^11.0` → `^11.0|^12.0`). CI fails because `gate certify --coverage=100` reports 68.2% coverage.

Blockers

This issue is blocked by the coverage issues:

• Write PhpStanPromptTransformer tests (coverage: 3.6% → 100%) #44 PhpStanPromptTransformer tests (3.6% → 100%)
• Write TestFailurePromptTransformer tests (coverage: 11.7% → 100%) #45 TestFailurePromptTransformer tests (11.7% → 100%)
• Write ChecksClient.postActionablePrompt() tests (coverage: 89.1% → 100%) #46 ChecksClient.postActionablePrompt tests (89.1% → 100%)
• Write PromptAssembler tests (coverage: 88.9% → 100%) #47 PromptAssembler tests (88.9% → 100%)
• Refactor and test AnalyzeCommand (coverage: 0% → 100%) #48 AnalyzeCommand refactor + tests (0% → 100%)
• Refactor and test CheckCommand (coverage: 0% → 100%) #49 CheckCommand refactor + tests (0% → 100%)
• Fix SymfonyProcessRunner exception handling (production bug) #50 ProcessRunner exception handling fix
• Fix ChecksClient.logError() type safety (hasResponse on GuzzleException) #51 ChecksClient.logError type safety fix

Impact

Gate CI red blocks:

• conduit-ui/knowledge CI (uses gate@v1 action)
• 7 pending PRs on the-shit/music
• Any other repo using gate for quality checks

Acceptance

• `php vendor/bin/pest --coverage` shows 100% total coverage
• `php gate certify --coverage=100` passes
• CI green on PR feat: add Laravel Zero 12 support #43
• Tag and release new version