Feat/token metadata caching

[K1NGD4VID]

Summary

Related issue

Type of change

• Bug fix
• New feature
• Refactor
• Docs
• Tests
• CI / tooling

Checklist

• I have read CONTRIBUTING.md
• npx tsc --noEmit passes
• npm run build passes
• I added / updated tests where relevant
• I updated docs where relevant

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[Miracle656]

Token metadata caching is the right approach for #37. Three things to address:

1. Remove scratch/generate_fixtures.js
Same as #45 — this debug script shouldn't be committed. git rm scratch/generate_fixtures.js.

2. Stacked on #45
Your diff includes all of #45's changes (decoder rename, decoder tests, fixtures). If #45 merges first your diff will shrink automatically to just the caching additions. Please either: (a) wait for #45 to merge and rebase, or (b) confirm you want this PR to supersede #45 and we'll close that one.

3. prisma/schema.prisma changes
You're adding to the Prisma schema here and also in #48. Make sure only one PR owns schema changes to avoid conflicts.

[K1NGD4VID]

I've addressed the feedback for both PR #37 (feat/token-metadata-caching) and PR #45 (test/xdr-decoder-unit-tests).

Here’s the summary of the changes:

Removed scratch/generate_fixtures.js: I've removed this script from the feat/token-metadata-caching branch. I also ensured it was cleaned up on the test/xdr-decoder-unit-tests branch as previously requested.
Stacked on #45: I've rebased feat/token-metadata-caching onto test/xdr-decoder-unit-tests. This ensures that once #45 is merged into main, the diff for the caching PR will automatically shrink to only show the metadata caching logic.
Resolved Prisma Schema Conflict: To address the concern about multiple PRs owning schema changes, I've rebased feat/accounts-balance-endpoint (#48) onto feat/token-metadata-caching (#37). This makes #37 the "owner" of the TokenMetadata model in the schema, while #48 now simply inherits it as part of its base.
Updated Branch State:

feat/token-metadata-caching: Rebased on #45, script removed, force-pushed.
feat/accounts-balance-endpoint: Rebased on #37, force-pushed.
Everything is now cleanly organized and ready for the next round of reviews!

[Miracle656]

Good progress — scratch/generate_fixtures.js is gone. The token metadata cache (memory → DB → RPC) is the right architecture.\n\nOne thing to fix before merging:\n\nRebase on main — PR #45 (XDR decoder) merged today, so your branch still carries all of #45's changes in the diff. After rebasing, the diff will shrink to just the caching-related additions (tokenCache.ts, tokenCache.test.ts, schema changes, etc.) making it much easier to review in isolation.\n\n\ngit fetch origin\ngit rebase origin/main\ngit push --force-with-lease\n\n\nOnce rebased I'll approve immediately.