Enhancement: Enforce PRs use .github/PULL_REQUEST_TEMPLATE.md in automated flows

## Problem
Automated PR creation (local/scripts/Actions) can drift from our `.github/PULL_REQUEST_TEMPLATE.md` guidance and sometimes introduces formatting issues.

## Proposal
- Standardize on creating PR bodies via `--body-file` or API payloads sourced from a rendered template
- Add helper that composes the standard sections (Summary, What Changed, Why, References, Git Statistics)
- Integrate into close-issue and auto-trigger workflows

## Acceptance Criteria
- All automated PRs follow the template’s structure
- No escaped newlines; markdown renders correctly
- Documented procedure for local/manual usage

## Related
- Follow-up to bug filed separately
- `.github/PULL_REQUEST_TEMPLATE.md`

Start by reading .github/PULL_REQUEST_TEMPLATE.md and tracing the automated PR creation paths under local/scripts/Actions, including the close-issue and auto-trigger workflows. Done means every automated PR uses the template structure, renders markdown without escaped newlines, and has a documented local/manual procedure.

Written by the indexing model from the issue text.