fix(checker): report error when using bigint as enum key

[magic-akari]

• Fixes enum member key should reject bigint #61772

[Copilot]

Pull Request Overview

This PR introduces a diagnostic change in the checker to report an error when a bigint literal is used as an enum key, and updates tests and baseline files accordingly.

• Added a test case (enumWithBugint.ts) that defines an enum using a bigint literal as a key.
• Updated the TypeScript checker logic to emit an error for numeric and BigInt literals used as enum member names.
• Refreshed baseline files (types, symbols, JS, errors) to reflect the updated diagnostic messages.

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

File	Description
tests/cases/compiler/enumWithBugint.ts	New test case to verify error reporting for bigint enum keys
tests/baselines/reference/enumWithBugint.{types,symbols,js,errors.txt}	Updated baselines to accommodate the new error message
src/compiler/checker.ts	Added error checking for BigInt literals in enum member names