docs(ai-team-orchestration): add role guidance, PR checklist, QA risk matrix, and sample prompts (#2946)

Improve the ai-team-orchestration skill references:
- anti-patterns.md: Do/Don't role responsibilities (Producer/Dev/QA) and decision-log guidance
- brainstorm-format.md: minimal sample prompts for Producer, Dev, and QA agents
- sprint-plan-template.md: concrete acceptance-criteria examples, PR checklist, and a QA risk matrix
- project-brief-template.md: onboarding checklist and where to record decisions

Co-authored-by: sinamorida <sinamorida@users.noreply.github.com>
Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Aaron Powell <me@aaron-powell.com>

skills/ai-team-orchestration/references/sprint-plan-template.md

@@ -32,20 +32,41 @@ Use this for substantial work. Small, clear changes can proceed directly from th
 ## Acceptance Criteria
 
 - [ ] [observable behavior]
-- [ ] Relevant repository checks pass
+- [ ] Relevant repository checks pass (example: `npm run lint`, `npm test`)
+- [ ] Tests covering the change are added or validated
 - [ ] Documentation/context is updated when behavior or operation changed
 
 ## Verification
 
 - Automated: [commands or checks]
+  - Example: `npm ci && npm run test` or `pytest -q`
+  - Example: `npm run lint && npm run build`
 - Manual: [focused scenarios, if useful]
 - Independent review: required / optional / not needed - [reason]
 - QA: required / optional / not needed - [reason]
 
+## PR Checklist (add to PR body)
+
+- Branch name follows repo policy (e.g., `feat/`, `fix/`, or `chore/`)
+- Description: short summary, why, and acceptance criteria
+- Verification steps included (commands & manual checks)
+- Tests added or existing tests updated
+- Relevant docs/PROJECT_BRIEF updated if behavior changed
+- Reviewers: @team or specific owners
+- Required checks: list CI jobs that must pass
+- Release notes / changelog entry: yes/no
+
 ## Risks and Decisions
 
 - [risk or material decision]
 
+## QA risk matrix (when to require QA)
+
+- High impact × High uncertainty = QA required
+- High impact × Low uncertainty = QA recommended
+- Low impact × High uncertainty = QA recommended
+- Low impact × Low uncertainty = QA optional
+
 ## Next Action
 
 [owner and immediate next step]