docs: add review-plan command + rules templates (inspired by Garry Tan)

Structured plan review across 4 axes (architecture, code quality, tests,
performance) as a reusable custom command with separate rules files.

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

examples/rules/code-quality-review.md

@@ -0,0 +1,33 @@
+---
+description: "Code quality review criteria for plan and code reviews"
+---
+
+# Code Quality Review Criteria
+
+When reviewing code quality, evaluate these dimensions:
+
+## Organization
+- Is the module structure logical and consistent?
+- Are files in the right directories?
+- Is the naming convention consistent across the codebase?
+
+## DRY Violations
+- Flag any duplicated logic (be aggressive)
+- Identify copy-paste patterns that should be abstracted
+- Check for repeated configuration or magic values
+
+## Error Handling
+- Are errors handled at the right level (not swallowed, not over-caught)?
+- Are edge cases explicitly handled or documented as out-of-scope?
+- Do error messages provide enough context for debugging?
+- Are there silent failures (empty catch blocks, ignored return values)?
+
+## Technical Debt
+- Which areas have the highest maintenance burden?
+- Are there TODO/FIXME comments that should be addressed now?
+- Is there dead code that should be removed?
+
+## Engineering Balance
+- Are there areas that are over-engineered (premature abstraction, unnecessary complexity)?
+- Are there areas that are under-engineered (fragile, hacky, missing validation)?
+- Does the complexity match the actual requirements?