docs/chore: fix broken README code span and align package license with LICENSE

[Arismemo]

Summary

Two small metadata/doc fixes, no code changes:

1. README — the `ASH_ALLOWED_EXTS=.md,.json,…` inline code opened with a backtick but closed with `)`, so the rest of the "Upload whitelist & limits" paragraph rendered as a code span. Replaced the stray `)` with the closing backtick.
2. package.json / package-lock.json — `license` was `ISC`, but the repo's `LICENSE` file and README both say MIT. Aligned the manifest (and the lockfile's root entry, so a future `npm install` doesn't produce an unrelated diff).

Verification

• `node -e 'require("./package.json")'` / lockfile both parse; root license reads `MIT`
• README line now has an even number of backticks (4), so both code spans close

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