Add native Crystal exploration port and reference tooling

reference/public/vendor/binjgb/PROVENANCE.md

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+# binjgb
+
+Source: https://github.com/binji/binjgb
+
+Pinned commit: `c60e138da5a795ebb55e56b11b7e90024e41112c`.
+
+`binjgb.js` and `binjgb.wasm` are unmodified files from that commit's `docs/` directory. `LICENSE` is the upstream MIT license. No upstream demo ROMs, images, game data, or boot ROMs are included. The app uses the emulator's direct cartridge startup.
+
+Run `npm run check:vendor` to verify SHA-256 checksums. Fetch replacements only from an explicitly pinned upstream commit, review the source and license, update the checksums, and run the synthetic-ROM integration tests. A core update also needs a save-state migration decision; never silently use old binary states with a different core ID.
+
+The app's adapter was written against the upstream exported API and embedding example: https://github.com/binji/binjgb/blob/c60e138da5a795ebb55e56b11b7e90024e41112c/docs/simple.js