0.0.4

0.0.4 — Bootstrap onboarding

• Bootstrap an existing vault (filename trekey prefixes, no tags yet):
  decompose a filename trekey into a hierarchical location tag
  (S88B07 → #trel/S88/B/07). Placeholder slots (0/00) are kept as tag
  segments so the tag ↔ trekey round-trip stays exact.
• Dry-run preview command — lists every file's proposed tag (and files
  skipped because they're already tagged or have no recognizable trekey).
  Writes nothing.
• Apply writes the tag into each file's frontmatter (existing content
  preserved) and records what it wrote.
• Undo last bootstrap command reverts exactly those writes.