Add idempotent job creation foundation

[chubes4]

Summary

• Add nullable idempotency_key storage with a unique jobs-table index and idempotent upgrade path.
• Add Jobs::create_or_get_job() and get_job_by_idempotency_key() so repeated deterministic keys return the existing job with created=false / already_exists=true.
• Add PHPUnit coverage for repeated idempotent creation and missing-key validation.

Notes

• I did not wire a runtime child-job creation path in this PR because the existing pipeline fan-out path also schedules follow-up work; safely returning an existing child needs additional coverage that duplicate chunks do not reschedule steps.

Tests

• php -l inc/Core/Database/Jobs/Jobs.php && php -l tests/Unit/Core/Database/JobLifecycleTransitionTest.php
• composer test (Homeboy/WP Codebox): 1366 total, 1362 passed, 4 skipped
• composer lint

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (gpt-5.5)
• Used for: Drafted the repository implementation, migration path, and PHPUnit coverage; Chris remains responsible for review and validation.

[homeboy-ci]

Homeboy Results — data-machine

Lint

✅ lint — passed

ℹ️ Full options: homeboy docs commands/lint
Deep dive: homeboy lint data-machine --changed-since ec77897

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-data-machine-lint-quality-Linux-node24 contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-data-machine-lint-quality-Linux-node24 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/data-machine/actions/runs/27802130651

Test

✅ test — passed

• 867 passed
• 4 skipped

ℹ️ Auto-fix lint issues: homeboy refactor data-machine --from lint --write
ℹ️ Collect coverage: homeboy test data-machine --coverage
ℹ️ Save test baseline: homeboy test data-machine --baseline
ℹ️ Pass args to test runner: homeboy test -- [args]
ℹ️ Full options: homeboy docs commands/test
Deep dive: homeboy test data-machine --changed-since ec77897

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-data-machine-test-quality-Linux-node24 contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-data-machine-test-quality-Linux-node24 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/data-machine/actions/runs/27802130651

Audit

✅ audit — passed

• audit — 128 finding(s)
• Total: 128 finding(s)

Deep dive: homeboy audit data-machine --changed-since ec77897

Artifacts and drill-down

• CI results artifact: homeboy-ci-results-data-machine-audit-quality-Linux-node24 contains immediate command JSON for this action invocation.
• Observation artifact: homeboy-observations-data-machine-audit-quality-Linux-node24 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/data-machine/actions/runs/27802130651

Tooling versions

• Homeboy CLI: homeboy 0.243.0+4d739ef997de+8e2add37
• Extension: wordpress from https://github.com/Extra-Chill/homeboy-extensions
• Extension revision: d910ef1e
• Action: unknown@unknown