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

.gitignore

@@ -2,6 +2,11 @@
 # Never commit ROMs/patches; this folder is per-machine scratch.
 drop/
 
+# Output of the archived build-romhack-vault.py. The canonical catalog lives in
+# the self-hosted Obsidian vault (Pokémon ROM Hacks/), not here — never commit
+# a regenerated, poorer copy back into this repo.
+pokemon-romhack-vault/
+
 # OS / editor cruft
 .DS_Store
 Thumbs.db