feat(meta): add .github/ISSUE_TEMPLATE/ and PULL_REQUEST_TEMPLATE.md to lower contribution friction

## Summary

`drbothen/vsdd-factory` has no issue templates and no PR template. Contributors filing bug reports / feature requests have to construct the structure from scratch each time, and the result varies in quality.

This issue itself is filed without a template; you can see the structure I've adopted by convention from reading other recent issues (#172, #130). Codifying that into a template would lower the bar.

## Proposed

### `.github/ISSUE_TEMPLATE/bug_report.yml`

Standard GitHub bug report form with:
- `vsdd-factory version` (text)
- `Operator's project language` (Rust / Go / Python / Node / Other)
- `Summary` (textarea, required)
- `Repro steps` (textarea, required)
- `Expected vs actual` (textarea)
- `Plugin install method` (claude-mp / cargo / git clone)
- `OS / shell` (text)
- `Related issues` (text)
- Label auto-application: `bug`

### `.github/ISSUE_TEMPLATE/feature_request.yml`

- `Summary` (textarea, required)
- `Problem being solved` (textarea, required)
- `Proposed behavior` (textarea, required)
- `Acceptance criteria` (textarea)
- `Found during` / motivating use case (textarea)
- Label auto-application: `enhancement`

### `.github/ISSUE_TEMPLATE/config.yml`

Disable blank issues; route to discussions for questions:
```yaml
blank_issues_enabled: false
contact_links:
- name: VSDD Discussion
url: https://github.com/drbothen/vsdd-factory/discussions
about: Questions, design discussion, ideas not yet a concrete issue
```

### `.github/PULL_REQUEST_TEMPLATE.md`

```markdown
## Summary

## Linked issues

Closes #...

## Changes

## Testing

- [ ] Existing bats tests pass: `bats plugins/vsdd-factory/tests/`
- [ ] New tests added for new behavior (if applicable)
- [ ] Manual repro performed (steps below)

## Iron Law / Red Flag impact

## Checklist

- [ ] Conventional commit subject (`feat(scope): ...` / `fix(scope): ...`)
- [ ] No AI attribution in commits or this PR body
- [ ] Templates referenced as `${CLAUDE_PLUGIN_ROOT}/templates/...`, never `.claude/templates/`
```

## Acceptance criteria

- [ ] `.github/ISSUE_TEMPLATE/bug_report.yml` exists with the fields above.
- [ ] `.github/ISSUE_TEMPLATE/feature_request.yml` exists.
- [ ] `.github/ISSUE_TEMPLATE/config.yml` disables blank issues.
- [ ] `.github/PULL_REQUEST_TEMPLATE.md` references CONTRIBUTING.md's Iron Law / Red Flag policy and the no-AI-attribution rule.
- [ ] Templates apply on next issue/PR creation.

## Found during

Filing issues #203-#209 against vsdd-factory (2026-06-23). I followed the structure I'd seen in existing issues (#172, #130) but the project would benefit from codifying that into a template.