fix: make check-format portable on Windows

[SyntaxSawdust]

Summary

• Remove the trailing semicolon from the check-format npm script.

Why

• Two upstream PR validation notes (#2212, #2250) report that
  npm run check-format passes ESLint and Prettier on Windows, then exits
  non-zero because the script's trailing .; is parsed as an extra Prettier
  path.
• Upstream package.json still contained the trailing semicolon. This keeps the
  same ESLint/Prettier checks and removes only the shell-sensitive terminator.

Tests

• npm ci (passed; npm reported 17 moderate audit findings unrelated to this
  dependency-free diff)
• npm run check-format (passed)
• git diff --check (passed)
• npm run build (fails with an unrelated TypeScript declaration conflict in
  node_modules/chrome-devtools-frontend/front_end/models/trace/ModelImpl.ts:230)

Scope / non-goals

• Scope: package.json script cleanup only.
• Non-goals: no lint/format toolchain changes, dependency changes, generated
  file updates, or issue creation.

Caveats

• No dedicated issue exists; this references the PR validation notes as evidence
  rather than closing an issue.
• Windows-specific behavior was not reproduced locally on this macOS checkout;
  the premise comes from the linked upstream validation notes.
• Broader npm run build currently fails in an unrelated dependency TypeScript
  declaration.

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