[Code Quality] Add engine.extensions section to concise frontmatter reference docs

[github-actions]

Description

engine.extensions is a supported frontmatter field implemented in pkg/workflow/pi_engine.go and defined in pkg/parser/schemas/main_workflow_schema.json, but the concise frontmatter reference (docs/src/content/docs/reference/frontmatter.md) documents engine.driver (lines 151-161) with no corresponding engine.extensions section.

Users who read only the top-level reference (the most common entry point) will not discover this supported field; they must navigate to the specialized engines page.

Suggested Changes

• Add an engine.extensions subsection to docs/src/content/docs/reference/frontmatter.md near the engine.driver section
• Describe what the field does (emits pi install <extension> steps) and its expected format
• Cross-reference the engines reference page for full details

Files Affected

• docs/src/content/docs/reference/frontmatter.md (around lines 151-161)

Success Criteria

• engine.extensions is documented in the concise frontmatter reference
• The documentation is consistent with docs/src/content/docs/reference/engines.md:435-447
• No regressions in doc generation

Source

Extracted from Schema Consistency Check - 2026-07-20 #46731

Priority

Low - Documentation gap for a valid supported feature. Effort: <1 hour.

🔍 Task mining by Discussion Task Miner - Code Quality Improvement Agent · 35.6 AIC · ⌖ 5.2 AIC · ⊞ 7K · ◷

• expires on Jul 21, 2026, 5:27 AM UTC-08:00

[github-actions]

This issue was automatically closed because it expired on 2026-07-21T13:27:13.190Z.

Closed by Workflow