Merge Document Archive, Frontmatter Taxonomy, and archiving instructions into one unified section. Add guides for all vault areas (journals, notes, trip plans, writing, documents). Add When Nothing Fits fallback rule.
- VAULT_MAP.md: comprehensive guide for LLMs and agents covering people, folder structure, naming conventions, frontmatter taxonomy (15 categories + 25 types), disambiguation rules, and search info - README.md: updated with pointer to VAULT_MAP.md
