test: browser test runner

[JoTurk]

• Run the test on real browsers in the CI.
• Added helpers to run tests.
• Added a lambdatest helper.
• code coverage.
• added an example for running tests in the browser.

[codecov]

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[Copilot]

Pull Request Overview

This PR modernizes the testing infrastructure by migrating from Vitest v3 to v4, implementing browser-based testing with WebDriverIO, and adding LambdaTest integration for cross-browser testing in CI/CD.

Key changes include:

• Migration to Vitest v4 with separate Node.js and browser test projects
• Addition of WebDriverIO-based browser testing with support for Chrome, Firefox, Edge, and Safari
• Integration with LambdaTest for cloud-based cross-browser testing
• Replacement of self.fetch with globalThis.fetch for better cross-environment compatibility

Reviewed Changes

Copilot reviewed 12 out of 14 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
vitest.config.ts	Adds comprehensive browser testing configuration with WebDriverIO provider and LambdaTest support
src/ui/UIMetrics.browser.spec.ts	New browser-specific test for UIMetrics component
src/Util.ts	Updates fetch implementation to use globalThis instead of self
src/Util.spec.ts	Updates tests for globalThis.fetch and adds browser environment compatibility
src/EventEmitter.spec.ts	Adds mockClear to prevent test interference
src/Connect.spec.ts	Updates invalid URL test case
scripts/run-lambdatest.ts	New script for managing LambdaTest browser matrix selection and test execution
package.json	Updates dependencies to Vitest v4 and adds browser testing packages
.husky/pre-push	Updates to use new test script
.gitignore	Adds test-related ignore patterns
.github/workflows/test.yaml	New GitHub Actions workflow for matrix testing across browsers and platforms
.github/workflows/test-node.yml	Removed in favor of new test.yaml workflow
.codecov.yml	Removes comment configuration

Comments suppressed due to low confidence (1)

src/Util.spec.ts:310

• The describe blocks 'path functions' and 'string trim functions' are incorrectly nested inside the it('should throw on error response') test at line 260. This will cause these test suites to never execute. These describe blocks should be moved outside and at the same level as the 'fetch' describe block.

            describe('path functions', () => {
                it('should get extension from path', () => {
                    expect(Util.getExtension('file.txt')).toBe('.txt');
                    expect(Util.getExtension('path/to/file.txt')).toBe('.txt');
                    expect(Util.getExtension('file')).toBe('');
                    expect(Util.getExtension('path/to/file.txt')).toBe('.txt');
                    expect(Util.getExtension('path/to/.txt')).toBe('.txt');
                    expect(Util.getExtension('.txt')).toBe('.txt');
                    expect(Util.getExtension('path/to/file.txt.')).toBe('.');
                });

                it('should get file from path', () => {
                    expect(Util.getFile('file.txt')).toBe('file.txt');
                    expect(Util.getFile('path/to/file.txt')).toBe('file.txt');
                });

                it('should get base file without extension', () => {
                    expect(Util.getBaseFile('file.txt')).toBe('file');
                    expect(Util.getBaseFile('path/to/file.txt')).toBe('file');
                    expect(Util.getBaseFile('file')).toBe('file');
                });
            });

            describe('string trim functions', () => {
                it('should trim spaces', () => {
                    expect(Util.trim('  hello  ')).toBe('hello');
                });

                it('should trim custom characters', () => {
                    expect(Util.trim('xxhelloxx', 'x')).toBe('hello');
                    expect(Util.trim('xxhello😭xx', 'x😭')).toBe('hello');
                });

                it('should trim start only', () => {
                    expect(Util.trimStart('  hello  ')).toBe('hello  ');
                    expect(Util.trimStart('😭hello😭', '😭')).toBe('hello😭');
                });

                it('should trim end only', () => {
                    expect(Util.trimEnd('  hello  ')).toBe('  hello');
                    expect(Util.trimEnd('😭hello😭', '😭')).toBe('😭hello');
                });
            });

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