feat(docs): add LLM Handbook + Google Whitepaper integration v3.3.0

Advanced Guardrails:
- prompt-injection-detector.sh (PreToolUse)
- output-validator.sh (PostToolUse heuristics)
- claudemd-scanner.sh (SessionStart injection detection)
- output-secrets-scanner.sh (PostToolUse secrets leak prevention)

Observability & Monitoring:
- session-logger.sh (JSONL activity logging)
- session-stats.sh (cost tracking & analysis)
- guide/observability.md (full documentation)

LLM-as-a-Judge Evaluation:
- output-evaluator.md agent (Haiku)
- /validate-changes command
- pre-commit-evaluator.sh (opt-in git hook)

Google Agent Whitepaper Integration:
- Context Triage Guide (Section 2.2.4)
- CLAUDE.md Injection Warning (Section 3.1.3)
- Agent Validation Checklist (Section 4.2.4)
- MCP Security: Tool Shadowing & Confused Deputy (Section 8.6)
- Session vs Memory patterns (Section 3.3.3)

Stats: 10 new files, 8 modified, 5 new guide sections

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

guide/README.md

@@ -9,6 +9,8 @@ Core documentation for mastering Claude Code.
 | [ultimate-guide.md](./ultimate-guide.md) | Complete reference covering all Claude Code features | ~3 hours |
 | [cheatsheet.md](./cheatsheet.md) | 1-page printable quick reference | 5 min |
 | [adoption-approaches.md](./adoption-approaches.md) | Implementation strategies for teams | 15 min |
+| [data-privacy.md](./data-privacy.md) | Data retention and privacy guide | 10 min |
+| [observability.md](./observability.md) | Session monitoring and cost tracking | 15 min |
 
 ## Recommended Reading Order