chore(pr-template): commit-prefix + dual-changelog checklist (#71)

- Drops the hardcoded 34/34 verify-plugin.sh count (current pass count
  is 56+; bare 'passes' avoids future bit-rot)
- New checkbox flagging the semantic-scope-not-version-prefix rule with
  cross-ref to CONTRIBUTING.md
- Disambiguates which CHANGELOG to edit: plugins/preview-forge/CHANGELOG.md
  is hand-maintained; the root CHANGELOG.md is regenerated by
  release-please and must not be hand-edited (avoids release-PR conflicts)
- Reminds authors not to hand-bump version — release-please owns
  marketplace.json + plugin.json sync

Closes #71 part 2 (PR template).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: sgwannabe

.github/PULL_REQUEST_TEMPLATE.md

@@ -15,13 +15,14 @@
 
 ## Checklist
 
-- [ ] `bash scripts/verify-plugin.sh` passes (34/34 checks)
+- [ ] `bash scripts/verify-plugin.sh` passes
 - [ ] Agent count still 143 (or I've updated the proposal + CHANGELOG explicitly)
 - [ ] All agents still use `model: opus` (no Sonnet/Haiku)
 - [ ] No third-party service dependencies (no Figma / Google / external CDN)
 - [ ] Layer-0 rules respected (`methodology/global.md`)
-- [ ] `version` bumped in both `.claude-plugin/marketplace.json` and `plugins/preview-forge/.claude-plugin/plugin.json` if this is a release
-- [ ] `CHANGELOG.md` entry added
+- [ ] Commit prefix uses **semantic scope** (e.g. `fix(cache):`, `feat(security):`), **not** a version prefix (`fix(v1.X.Y):`) — release-please autobumps semver from Conventional Commits, so version scopes are redundant. See `CONTRIBUTING.md → Commit message convention`.
+- [ ] `plugins/preview-forge/CHANGELOG.md` (hand-maintained) updated if user-visible plugin behavior changed. **Do not** edit the root `CHANGELOG.md` — it is regenerated by release-please from Conventional Commits. `memory/PROGRESS.md` / `memory/LESSONS.md` updated if applicable.
+- [ ] `version` is **not** hand-bumped — release-please owns `.claude-plugin/marketplace.json` + `plugins/preview-forge/.claude-plugin/plugin.json` version sync
 
 ## Related