feat(vault): synthesize Discord scrape + web research into the ROM-hack catalog

Enrich the Obsidian ROM-hack vault from the valhalla Discord scrape
(/storage1/labdata/romhacks/metadata) plus web research, growing the catalog
from 285 to 368 notes and preparing a data export for a wiki site.

Tooling (all dry-run by default, --apply to write; .scrape/ is gitignored):
- scrape_match.py    reconcile scrape entries vs notes (43 overlap / 211 match / 83 new)
- enrich_vault.py    backfill frontmatter, merge scrape into curated notes,
                     create 83 new notes, rebuild import bodies to one layout
- enrich_web.py      apply hand/web-verified facts from .scrape/web_facts*.json
- build-wiki-data.py export wiki/catalog.json (the site data source)

Results: 368 notes, 327 with served banner art, 332 rich summaries, 200 with
feature lists; new frontmatter developer/release_date/banner/homepage/scrape_dir;
12 flagship hacks web-verified. wiki/SPEC.md describes the site build.
build-vault-mocs.py Index callout updated for the new counts.

.gitignore

@@ -16,3 +16,9 @@ Thumbs.db
 # Local scratch
 *.tmp
 *.log
+
+# Discord-scrape metadata pulled from valhalla for enrichment runs (per-machine
+# scratch; the canonical synthesis lands in the Obsidian vault notes).
+.scrape/
+.scrape_lib/
+scripts/__pycache__/