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

[sinamorida]

Summary

Small, additive improvements to the ai-team-orchestration skill references so agents get concrete, actionable guidance instead of inferring it:

• anti-patterns.md — add a short Do / Don't section for Producer, Dev, and QA role boundaries, plus concise decision-log guidance (what to record and where).
• brainstorm-format.md — add three minimal, copy-paste sample prompts (Producer, Dev, QA) so the personas are easy to invoke without rewriting them each time.
• sprint-plan-template.md — add concrete acceptance-criteria examples, a PR checklist (branch naming, verification steps, reviewers, required checks, release notes), and a simple 2x2 QA risk matrix for deciding when QA is required vs optional.
• project-brief-template.md — add an onboarding checklist and a short "where to record decisions" note.

Everything is additive; no existing guidance is removed or contradicted.

Verification

• Reviewed the final diff (69 insertions, 1 deletion across 4 markdown files).
• Confirmed the four reference files exist upstream at skills/ai-team-orchestration/references/ and edits apply cleanly on top of main.

Limitations

• Documentation-only change; no code or behavior affected.

[github-actions]

🔒 PR Risk Scan Results

Scanned 4 changed file(s).

Severity	Count
🔴 High	0
🟠 Medium	0
ℹ️ Info	0

✅ No matching risk patterns were detected in changed files.

This is an automated soft-gate report. Findings indicate review targets and do not block merge by themselves.

[github-actions]

🔍 Vally Lint Results

✅ All checks passed

Scope	Checked
Skills	1
Agents	0
Total	1

Severity	Count
❌ Errors	0
⚠️ Warnings	0
ℹ️ Advisories	0

Summary

Level	Finding
ℹ️	✅ ai-team-orchestration (2/2 checks passed)
ℹ️	✓ [spec-compliance] All 1 skill(s) are spec-compliant.
ℹ️	✓ spec-compliance: All spec checks passed.
ℹ️	✓ [valid-refs] All file references across 1 skill(s) are valid.
ℹ️	✓ valid-refs: All file references resolve to existing files within the skill directory.
ℹ️	1 skill(s) linted, 1 passed

Full linter output

### Linting skills/ai-team-orchestration
✅ ai-team-orchestration (2/2 checks passed)
    ✓ [spec-compliance] All 1 skill(s) are spec-compliant.
        ✓ spec-compliance: All spec checks passed.
    ✓ [valid-refs] All file references across 1 skill(s) are valid.
        ✓ valid-refs: All file references resolve to existing files within the skill directory.

1 skill(s) linted, 1 passed