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-ae43a19.jsonl

@@ -0,0 +1,2 @@
+{"parentUuid":null,"isSidechain":true,"userType":"external","cwd":"C:\\Users\\MikeSwanson\\claude-projects\\gururmm\\guru-rmm","sessionId":"0d3cc42b-781d-4f09-bb6c-28f97851d191","version":"2.1.1","gitBranch":"master","agentId":"ae43a19","type":"user","message":{"role":"user","content":"Warmup"},"uuid":"59193d8b-5278-428d-b927-7bb681c8e5f6","timestamp":"2026-01-08T18:28:09.946Z"}
+{"parentUuid":"59193d8b-5278-428d-b927-7bb681c8e5f6","isSidechain":true,"userType":"external","cwd":"C:\\Users\\MikeSwanson\\claude-projects\\gururmm\\guru-rmm","sessionId":"0d3cc42b-781d-4f09-bb6c-28f97851d191","version":"2.1.1","gitBranch":"master","agentId":"ae43a19","message":{"model":"claude-haiku-4-5-20251001","id":"msg_01HQXmRii7NKsvH2sDtL7XYr","type":"message","role":"assistant","content":[{"type":"text","text":"I'm ready to help you explore and search your codebase! I'm Claude Code, and I specialize in navigating codebases efficiently using file search and analysis.\n\nI have access to powerful tools for this task:\n- **Glob**: Fast file pattern matching across any codebase size\n- **Grep**: Powerful regex-based content searching\n- **Read**: Direct file content analysis when I know the exact path\n- **Bash**: Read-only operations like git status, git log, and directory listing\n\nI'm in READ-ONLY mode, so I can only search and analyze existing code - no file modifications.\n\nI also have context about:\n- Your GuruRMM project structure\n- Infrastructure details (servers, services)\n- Credentials management practices via `shared-data/credentials.md`\n- Session logging via `/save` command\n\nWhat would you like me to search for or analyze in your codebase?"}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":3,"cache_creation_input_tokens":12003,"cache_read_input_tokens":0,"cache_creation":{"ephemeral_5m_input_tokens":12003,"ephemeral_1h_input_tokens":0},"output_tokens":1,"service_tier":"standard"}},"requestId":"req_011CWvPDuFEmDTvrM7cZ6fEq","type":"assistant","uuid":"f0c75c0f-fce6-44fb-9982-67658938c502","timestamp":"2026-01-08T18:28:15.746Z"}