fix(tokenlist): dedupe post-build asset handling

[aproskill81]

Why

The tokenlist build was doing the same post-build work more than once.

We already handle copying data/ into dist and patching wrangler.json in vite.config.ts, but the build still also invoked scripts/postbuild.ts. On top of that, the Vite plugin was running in both the tokenlist and client environments, so the copy/patch step could run twice in a single build.

What changed

• removed the standalone scripts/postbuild.ts call from the build script
• kept the post-build logic in one place inside vite.config.ts
• limited the copy-assets plugin to the tokenlist environment so the asset copy and wrangler.json patch only run once