Security Fixes:
- Update vite from 5.3.3 to 7.2.2 (fixes multiple moderate/low severity issues)
- Update rollup from 4.18.1 to 4.53.2
- Update eslint from 9.7.0 to 9.39.1
- Update typescript from 5.5.3 to 5.6.3
- All security vulnerabilities resolved (0 known vulnerabilities)

Testing Infrastructure:
- Add vitest testing framework with happy-dom environment
- Add @testing-library/dom for enhanced DOM testing utilities
- Create vitest.config.ts with coverage configuration
- Add test setup file with font mocking for ESig component
- Add test scripts: test, test:ui, test:run, test:coverage

Test Coverage (119 tests, 111 passing):
- CSSVars utility: 8/8 tests passing
  - Variable extraction from template strings
  - Complex CSS values (gradients, calc, URLs)
  - Edge cases and whitespace handling

- ComponentDescriptor: 8/8 tests passing
  - Custom element descriptor creation
  - Extends element support
  - Style processing and theme management
  - Type safety validation

- SlideToggle component: 20/28 tests passing
  - Initialization and attributes
  - State management (activated property)
  - User interactions (click events)
  - DOM structure validation
  - Event dispatching

- ESig component: 33/33 tests passing
  - Font selection and rendering
  - Icon customization
  - Attribute change callbacks
  - Font picker modal functionality
  - Content handling (whitespace, special chars, etc.)

- Grimoire class: 42/42 tests passing
  - Configuration (theme modes: browser, class, custom, disabled)
  - Component definition and registration
  - Style extraction and injection
  - Custom element registration
  - Theme selector generation
  - Error handling

Code Quality Improvements:
- Remove console.log from production code (src/index.ts)
- Add check for already-defined custom elements before registration
- Improve error messages and handling

CI/CD:
- Add GitHub Actions workflow (.github/workflows/ci.yml)
- Automated testing on push and pull requests
- Security audit checks
- Build verification

The test suite provides comprehensive coverage of core functionality
with 93% of tests passing. Remaining failures are related to DOM
querying specifics with the Mote library wrapper and will be addressed
in future iterations.

The pnpm/action-setup@v4 action now automatically reads the version
from package.json's packageManager field, so we don't need to specify
it twice. This resolves the ERR_PNPM_BAD_PM_VERSION error in CI.

HTML <template> elements store their children in a DocumentFragment
accessible via template.content, not as direct children in the DOM.
Updated getInput() and getLabel() helpers to check template.content
first, with a fallback to direct children for compatibility.

This fixes all 8 failing SlideToggle tests. All 119 tests now pass.

Test Results:
- CSSVars: 8/8 passing
- ComponentDescriptor: 8/8 passing
- Grimoire: 42/42 passing
- ESig: 33/33 passing
- SlideToggle: 28/28 passing ✓ (was 20/28)

Total: 119/119 passing (100%)