Add LLM Safe Haven — multi-agent security hooks with fail-closed design

[pleasedodisturb]

Adds LLM Safe Haven to the Secrets Management & Isolation section.

• npx llm-safe-haven — detects 14 agents, installs fail-closed hooks, JSONL audit trail
• Hooks: bash firewall (exfil/destructive blocking), secret guard (credential write blocking), audit logger
• SHA256 integrity verification for installed hooks
• Per-agent ignore files (.cursorignore, .codeiumignore, .aiderignore, etc.)
• Zero dependencies, 27 kB, published on npm as llm-safe-haven@0.1.0