feat: Add multi-agent-guide skill and update reference-curator configs

- Add 91-multi-agent-guide skill for setting up multi-agent collaboration
  with templates for AGENTS.md, Claude, Gemini, Codex configs, and CI/CD
- Add USER-GUIDE.md for reference-curator documentation
- Update default paths in reference-curator configs to use
  ~/Documents/05_AI Agent/10_Reference Library/
- Update settings-audit-report.md

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

custom-skills/91-multi-agent-guide/templates/locks-yaml.yaml

@@ -0,0 +1,42 @@
+# Agent File Locks Registry
+# Location: .agent-state/locks.yaml
+#
+# This file tracks file/directory locks held by agents.
+# Agents must acquire locks before modifying files.
+
+version: "1.0"
+updated_at: "2025-01-29T00:00:00Z"
+
+# Lock Types:
+# - exclusive: Only one agent can modify (blocks all others)
+# - shared: Multiple can read, one can write
+# - override: Claude override for conflict resolution
+
+locks: []
+
+# Example lock entry:
+#
+# locks:
+#   - path: "src/core/"
+#     agent: "claude"
+#     lock_type: "exclusive"
+#     task_id: "TASK-001"
+#     reason: "Refactoring core module"
+#     created_at: "2025-01-29T10:00:00Z"
+#     expires_at: "2025-01-29T14:00:00Z"
+#
+#   - path: "docs/api/"
+#     agent: "gemini"
+#     lock_type: "shared"
+#     task_id: "TASK-002"
+#     reason: "Updating API documentation"
+#     created_at: "2025-01-29T11:00:00Z"
+#     expires_at: "2025-01-29T15:00:00Z"
+#
+#   - path: "tests/"
+#     agent: "codex"
+#     lock_type: "exclusive"
+#     task_id: "TASK-003"
+#     reason: "Adding comprehensive tests"
+#     created_at: "2025-01-29T12:00:00Z"
+#     expires_at: "2025-01-29T16:00:00Z"