refactor: notes live in the Obsidian vault, repo is tooling-only

Per the standing rule that Obsidian notes belong in the self-hosted vault, not
in project folders:

- rm pokemon-romhack-vault/ (redundant generated snapshot; the canonical,
  richer catalog lives in the vault under Pokémon ROM Hacks/)
- pokemon-romhacks-wanted.md -> moved into the vault as Pokémon ROM Hacks/Wanted.md
- .gitignore: ignore pokemon-romhack-vault/ (build script output) so a poorer
  regenerated copy can never be committed back
- build-romhack-vault.py: marked ARCHIVED; vault is now hand-maintained via MCP
- README: rewritten to point at the vault for the catalog

scripts/build-romhack-vault.py

@@ -1,5 +1,15 @@
 #!/usr/bin/env python3
-"""Generate an Obsidian vault documenting the Pokémon ROM-hacks in the library.
+"""[ARCHIVED] Bootstrap generator for the Pokémon ROM-hack vault.
+
+The canonical catalog now lives in the self-hosted Obsidian vault under
+`Pokémon ROM Hacks/`, hand-maintained via the Obsidian MCP (see that folder's
+`_Claude.md` for the add-a-hack checklist). The live vault has been enriched well
+beyond what this script emits (play_status, rating, Bases/, Play Queue) — so do
+NOT re-run this against it and sync back; you would regress the catalog. This is
+kept only for the structured `HACKS` dataset below. Its output dir
+`pokemon-romhack-vault/` is gitignored.
+
+Originally: generate an Obsidian vault documenting the Pokémon ROM-hacks.
 
 Emits, under  pokemon-romhack-vault/ :
   - Hacks/<Name>.md   one note per hack (YAML frontmatter + tags + summary)