Fix jobs page performance and enable parent/child expand UI

[chubes4]

Summary

• Fix slow JOIN performance — removes CAST(p.pipeline_id AS CHAR) from the jobs list query. MySQL now uses eq_ref on primary keys (best possible join type) instead of full table scans caused by the CAST preventing index usage.
• Add child_count to job rows — correlated subquery on the indexed parent_job_id column, so the frontend knows which rows are expandable without needing engine_data.
• Enable the parent/child expand UI — the hide_children filter, parent_job_id query parameter, expand/collapse React components, and CSS were already built in the workspace but never deployed. This commit completes the feature by fixing the SQL layer and updating hasChildren() to use child_count.

What changed

Backend (PHP)

• JobsOperations::get_jobs_for_list_table() — fixed VARCHAR/BIGINT JOIN (no more CAST), added child_count subquery
• Api/Jobs.php — already had parent_job_id and hide_children REST params (workspace only)
• GetJobsAbility.php — already had parent_job_id and hide_children support (workspace only)

Frontend (React)

• JobsTable.jsx — hasChildren() now checks child_count first, falls back to engine_data.batch
• api/jobs.js — already had fetchChildJobs() and hideChildren (workspace only)
• queries/jobs.js — already had useChildJobs() hook (workspace only)
• jobs-page.css — batch hierarchy styles (workspace only)

Performance improvement

Before: LEFT JOIN ... ON j.pipeline_id = CAST(p.pipeline_id AS CHAR)  → ALL scan
After:  LEFT JOIN ... ON j.pipeline_id = p.pipeline_id                → eq_ref on PK

Testing

• 873/873 tests pass (29 pre-existing failures on main, unchanged)
• Lint passes with no new findings
• EXPLAIN confirms optimal query plan: eq_ref joins + index-only child_count scan

[github-actions]

Homeboy Results — data-machine

Lint

⚡ Scope: changed files only

✅ lint (changed files only)

Test

⚡ Scope: changed files only

✅ test (changed files only)

Audit

⚡ Scope: changed files only

✅ audit (changed files only)

Tooling versions

• Homeboy CLI: homeboy 0.81.1+7ef43bfa
• Extension: wordpress from https://github.com/Extra-Chill/homeboy-extensions
• Extension revision: unknown
• Action: Extra-Chill/homeboy-action@v1

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Homeboy Action v1