Add CI workflow to test, lint and build

[Copilot]

This PR adds a comprehensive CI workflow that automatically tests, lints, and builds the vibe-dashboard project on every pull request and push to main/develop branches.

What's Added

A new CI workflow (.github/workflows/ci.yml) that:

• Runs on multiple triggers: Pull requests and pushes to main and develop branches
• Uses Node.js LTS: Ensures compatibility and stability with the latest Long Term Support version
• Uses efficient caching: pnpm store caching for faster subsequent runs
• Executes all quality checks:
  • pnpm lint - ESLint validation across all packages
  • pnpm test - Test execution (currently no tests configured, but ready for future)
  • pnpm build - TypeScript compilation and Vite production build
• Verifies build artifacts: Ensures the build process creates expected output files

Why This Matters

Previously, the repository only had a deployment workflow that runs on the main branch. This new CI workflow provides:

• Early feedback during development via pull request checks
• Quality assurance before code is merged
• Stable environment using Node.js LTS for consistent builds
• Consistent environment using the same tooling as production deployment

The workflow is designed to complement the existing deploy.yml workflow without conflicts, providing comprehensive automated testing for the development workflow.

Testing

The CI workflow has been validated to:

• ✅ Successfully run all commands in a clean environment
• ✅ Catch and fail on linting errors (tested with intentional ESLint violations)
• ✅ Catch and fail on TypeScript compilation errors
• ✅ Verify build artifacts are properly created
• ✅ Use efficient caching to minimize build times

Fixes #19.

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[Boshen]

@copilot remove this strategy

[Copilot]

Removed the strategy matrix section as requested. The CI now runs on a single job instead of multiple Node.js versions. (20ec90d)

[Boshen]

@copilot use node lts

[Copilot]

Changed to use Node.js LTS (lts/*) instead of specific versions. This provides better stability and automatically uses the latest LTS version. (20ec90d)