feat: fix CI error by removing --fix flag from lint script

[Copilot]

Problem

The CI workflow was failing during the lint step because the lint script in package.json included the --fix flag. Using --fix in CI environments is problematic because:

1. ESLint modifies files during the CI run to auto-fix issues
2. Those modifications aren't committed back to the repository
3. This violates CI best practices where checks should be read-only operations

Solution

Updated the package.json scripts to separate checking from fixing:

"lint": "yarn eslint . --ext .js,.jsx,.ts,.tsx",           // For CI - check only
"lint:fix": "yarn eslint . --ext .js,.jsx,.ts,.tsx --fix", // For local dev - auto-fix

This follows the standard practice where:

• CI runs yarn run lint to verify code quality without modifying files
• Developers run yarn run lint:fix locally to automatically fix linting issues

Verification

• ✅ Lint passes without the --fix flag
• ✅ All tests pass (13/13 test suites)
• ✅ Build compiles successfully
• ✅ Minimal change (only 2 lines modified in package.json)

Fixes the CI error referenced in #[issue_number]

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[bug] CI error needs to be fixed</issue_title>
<issue_description>See: https://github.com/casbin/casbin.js/actions/runs/18439949933/job/52538954771</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes #296

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