feat(skills): add document-review skill for brainstorm/plan refinement (#112)

Add optional review and refine step to workflows:brainstorm and workflows:plan
that checks documents for clarity, completeness, user intent, and YAGNI.

- New document-review skill with review questions and evaluation criteria
- Brainstorm Phase 4 offers "Review and refine" option
- Plan post-generation offers "Review and refine" after technical review
- Includes YAGNI-based simplification guidance
- Max 2 iteration rounds before suggesting to proceed

Co-authored-by: Kieran Klaassen <kieranklaassen@users.noreply.github.com>

plugins/compound-engineering/commands/deepen-plan.md

@@ -480,14 +480,14 @@ After writing the enhanced plan, use the **AskUserQuestion tool** to present the
 
 **Options:**
 1. **View diff** - Show what was added/changed
-2. **Run `/plan_review`** - Get feedback from reviewers on enhanced plan
+2. **Run `/technical_review`** - Get feedback from reviewers on enhanced plan
 3. **Start `/workflows:work`** - Begin implementing this enhanced plan
 4. **Deepen further** - Run another round of research on specific sections
 5. **Revert** - Restore original plan (if backup exists)
 
 Based on selection:
 - **View diff** → Run `git diff [plan_path]` or show before/after
-- **`/plan_review`** → Call the /plan_review command with the plan file path
+- **`/technical_review`** → Call the /technical_review command with the plan file path
 - **`/workflows:work`** → Call the /workflows:work command with the plan file path
 - **Deepen further** → Ask which sections need more research, then re-run those agents
 - **Revert** → Restore from git or backup