feat: publish versioned data exports

The metadata behind the verifier, the pack builder and the site is now
served as static files: a versioned JSON API, CSV extracts, a SQLite
snapshot, and a catalog carrying a SHA-256 for each artifact.

The gaps dataset covers both layers behind a layer column. It previously
held one row, the single platform-verification anomaly, while the page
offering it as a download led with the emulator-level count.

source_ref renders as a permalink pinned to the revision the profile
cites. When a profile declares two repositories, a path that belongs to
neither by name is left as plain code: a citation without a link still
names the file and the lines, a link to the wrong repository does not.

The table filter, focus outlines and tap targets are progressive
enhancement; the pages work without them.

scripts/generate_readme.py

@@ -476,6 +476,7 @@ def generate_readme(db: dict, platforms_dir: str) -> str:
             "- **Per-system pages** showing which emulators and platforms cover each console",
             "- **Gap analysis** identifying missing files and undeclared core requirements",
             f"- **Cross-reference** mapping files across {len(coverages)} platforms and {emulator_count} emulators",
+            "- **Versioned data access** through JSON, CSV and SQLite exports with published SHA-256 checksums",
             "",
             "## How it works",
             "",