Add memory files for review-plan and review-spec skills

Skill documentation for the new plan/spec review skills. Each file
covers purpose, usage, how it works, referenced best practice files,
and gotchas.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

memory/skill-review-spec.md

@@ -0,0 +1,32 @@
+# Skill: review-spec
+
+## Purpose
+Reviews a spec file against best practices for structure quality, requirement testability, security coverage, and API design. Ensures specs are implementation-ready before agents start coding.
+
+## Usage
+```
+/review-spec spec/authentication.md
+/review-spec          # reads SPEC.md and prompts to select
+```
+
+## How it works
+1. Loads 5 best practice files: spec-driven-development, test-driven-development, api-design, llm-code-security, security-architecture
+2. Reads the specified spec file and SPEC.md index
+3. Evaluates 4 dimensions: structure completeness, requirement quality, security coverage, testability
+4. Checks every numbered requirement for testability, unambiguity, and rationale
+5. Identifies missing requirements and scenarios
+6. Outputs a scored review (1-5 per area), critical issues, missing requirements/scenarios, and recommendations
+
+## Best practice files referenced
+- `~/dev/claude/projects/best-practices/spec-driven-development.md`
+- `~/dev/claude/projects/best-practices/test-driven-development.md`
+- `~/dev/claude/projects/best-practices/api-design.md`
+- `~/dev/claude/projects/best-practices/llm-code-security.md`
+- `~/dev/claude/projects/best-practices/security-architecture.md`
+- Plus any tech-stack-specific files from the index
+
+## Gotchas
+- Read-only skill (allowed-tools: Read, Glob, Grep, Bash cat/ls/find). Cannot edit files.
+- Relies on best-practices repo being cloned at `~/dev/claude/projects/best-practices/`
+- The `~/` path in the bang-command generates a validator warning but works in practice
+- Counts requirements and verifies summary counts -- catches stale counts after edits