feat: v7.0.0 — 6 new engineering skills, badges, milestone tracker, SKILL_REQUEST.md

New skills added to pm-engineering bundle (now 10 skills total):
- debugging-log-analyser: stack trace → structured root cause diagnosis + fix
- pr-description-writer: diff/commits → reviewer-ready PR description
- system-design-interview: full system design with capacity, components, trade-offs
- changelog-generator: git log → polished Keep a Changelog entry
- test-strategy-doc: spec/PRD → complete test strategy with P0/P1 test cases
- runbook-writer: operational runbooks with exact commands, rollback, and escalation

README updates:
- 5 shields.io badges (stars, skill count, version, install, license)
- "See It in Action" demo section
- pm-engineering added to Quick Install list
- Star Milestone Tracker (100/250/500/1000 stars roadmap)
- Engineering table extended from 4 to 10 skills (41–50)
- Article 14 link resolved from remote merge

Config updates:
- marketplace.json: v6.0.0 → v7.0.0, "106 skills"
- pm-engineering plugin.json: v1.0.0 → v2.0.0

New file: SKILL_REQUEST.md — community skill voting board

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

plugins/pm-engineering/skills/pr-description-writer/SKILL.md

@@ -0,0 +1,87 @@
+---
+name: pr-description-writer
+description: "Write a clear, structured pull request description from a git diff, branch summary, or commit list. Use when asked to write a PR description, draft a pull request, or document code changes. Produces a description with summary, motivation, changes made, testing steps, and reviewer guidance. Optimised for Opus 4.7 and newer models."
+---
+
+# PR Description Writer Skill
+
+Writes structured, reviewer-friendly pull request descriptions from a diff, commit list, or informal notes. Covers the what, why, and how-to-review so reviewers can start immediately.
+
+## Required Inputs
+
+Ask for these if not provided:
+- **What changed** (paste a git diff, `git log --oneline`, or describe the changes in plain English)
+- **Why it was changed** (the problem being solved or feature being added)
+- **How to test it** (any specific steps a reviewer needs to verify it works)
+- **Risk level** (low / medium / high — affects how much reviewer guidance to include)
+- **PR type** (feature / bug fix / refactor / dependency upgrade / config change / hotfix)
+
+## Output Structure
+
+### Title
+A clear, imperative-mood title under 72 characters:
+`[type]: [concise description of what changed]`
+
+Examples:
+- `feat: add rate limiting to the public API`
+- `fix: resolve race condition in session expiry`
+- `refactor: extract payment logic into PaymentService`
+
+### Summary
+2–3 sentences covering:
+- What this PR does (the change)
+- Why it was needed (the problem or goal)
+- The approach taken (at a high level)
+
+### Changes Made
+Bullet list of specific changes — one bullet per logical change, not per file:
+- Added [X] to handle [Y]
+- Refactored [A] to reduce [B]
+- Removed [C] as it was replaced by [D]
+- Updated [E] to fix [F]
+
+### Screenshots / Demo
+[If UI change: include before/after screenshots or a screen recording]
+[If API change: include example request/response]
+[If no visual change: this section can be omitted]
+
+### How to Test
+Step-by-step instructions a reviewer can follow:
+1. [Setup step if needed]
+2. [Action to take]
+3. [What to verify]
+4. [Edge case to check]
+
+Include any specific commands, test data, or environment flags needed.
+
+### Testing Checklist
+- [ ] Unit tests added/updated
+- [ ] Integration tests added/updated
+- [ ] Edge cases covered
+- [ ] Manual testing completed
+- [ ] No regressions in existing tests
+
+### Reviewer Notes
+Flag anything that warrants extra attention:
+- Areas of uncertainty where a second opinion is welcome
+- Deliberate trade-offs made (and why)
+- Out-of-scope items noticed but not addressed
+- Dependencies on other PRs (link them)
+
+### Related
+- Closes #[issue number] (if applicable)
+- Related to #[PR/issue number]
+
+## Quality Checks
+- [ ] Title is imperative mood and under 72 characters
+- [ ] Summary explains what AND why (not just what)
+- [ ] Changes list describes logical changes (not file-by-file changes)
+- [ ] Testing steps are reproducible by someone unfamiliar with the code
+- [ ] Risk-appropriate reviewer guidance is included
+
+## Example Trigger Phrases
+- "Write a PR description for these changes" + [paste diff or description]
+- "Draft a pull request for [feature]"
+- "I need a PR description — here's what I changed"
+- "Summarise these commits into a PR description"
+- "Write the PR body for this branch"