feat: Add Sequential Thinking to Code Review + Frontend Validation

Enhanced code review and frontend validation with intelligent triggers:

Code Review Agent Enhancement:
- Added Sequential Thinking MCP integration for complex issues
- Triggers on 2+ rejections or 3+ critical issues
- New escalation format with root cause analysis
- Comprehensive solution strategies with trade-off evaluation
- Educational feedback to break rejection cycles
- Files: .claude/agents/code-review.md (+308 lines)
- Docs: CODE_REVIEW_ST_ENHANCEMENT.md, CODE_REVIEW_ST_TESTING.md

Frontend Design Skill Enhancement:
- Automatic invocation for ANY UI change
- Comprehensive validation checklist (200+ checkpoints)
- 8 validation categories (visual, interactive, responsive, a11y, etc.)
- 3 validation levels (quick, standard, comprehensive)
- Integration with code review workflow
- Files: .claude/skills/frontend-design/SKILL.md (+120 lines)
- Docs: UI_VALIDATION_CHECKLIST.md (462 lines), AUTOMATIC_VALIDATION_ENHANCEMENT.md (587 lines)

Settings Optimization:
- Repaired .claude/settings.local.json (fixed m365 pattern)
- Reduced permissions from 49 to 33 (33% reduction)
- Removed duplicates, sorted alphabetically
- Created SETTINGS_PERMISSIONS.md documentation

Checkpoint Command Enhancement:
- Dual checkpoint system (git + database)
- Saves session context to API for cross-machine recall
- Includes git metadata in database context
- Files: .claude/commands/checkpoint.md (+139 lines)

Decision Rationale:
- Sequential Thinking MCP breaks rejection cycles by identifying root causes
- Automatic frontend validation catches UI issues before code review
- Dual checkpoints enable complete project memory across machines
- Settings optimization improves maintainability

Total: 1,200+ lines of documentation and enhancements

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

projects/msp-tools/guru-rmm/agent-aa5e61b.jsonl

@@ -0,0 +1,2 @@
+{"parentUuid":null,"isSidechain":true,"userType":"external","cwd":"C:\\Users\\MikeSwanson\\claude-projects\\gururmm\\guru-rmm","sessionId":"260bcb83-20ef-4bbd-91cd-251f66e8a643","version":"2.1.1","gitBranch":"master","agentId":"aa5e61b","type":"user","message":{"role":"user","content":"Warmup"},"uuid":"14a72272-ed66-409d-91fe-330e3d4092f5","timestamp":"2026-01-08T20:39:43.910Z"}
+{"parentUuid":"14a72272-ed66-409d-91fe-330e3d4092f5","isSidechain":true,"userType":"external","cwd":"C:\\Users\\MikeSwanson\\claude-projects\\gururmm\\guru-rmm","sessionId":"260bcb83-20ef-4bbd-91cd-251f66e8a643","version":"2.1.1","gitBranch":"master","agentId":"aa5e61b","message":{"model":"claude-opus-4-5-20251101","id":"msg_01WzFezqVcb9tPph93ZDcpGZ","type":"message","role":"assistant","content":[{"type":"text","text":"I'm ready to help you with your task. This appears to be a warmup message, so I'm prepared to explore your codebase and create implementation plans as needed.\n\nBased on the environment context, I can see you're working in the `guru-rmm` project directory, which is a custom RMM (Remote Monitoring and Management) system with a Rust server, React dashboard, and Rust agent.\n\nWhat would you like me to help you plan or explore today?"}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":3,"cache_creation_input_tokens":0,"cache_read_input_tokens":12193,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":0},"output_tokens":106,"service_tier":"standard"}},"requestId":"req_011CWvZFydP7s5kbU7n973vB","type":"assistant","uuid":"a861e5d3-7466-4fe1-ba40-330dd77e33eb","timestamp":"2026-01-08T20:39:52.731Z"}