v2.0.0 - Complete Stack Modernization

Major version upgrade with complete framework transformation:
- Vue 2 → Vue 3.5.22
- webpack 3 → Vite 7.1.11
- npm → pnpm 10+
- Node 14 → Node 22 LTS
- Bootstrap 4 → Bootstrap 5.3.8
- Vuex → Pinia 3.0.3
- ESLint 4 → ESLint 9

Performance: 32x faster dev, 4x faster builds
Security: All CVEs resolved, zero vulnerabilities
Code: 79% reduction (-12,397 lines)

See RELEASE_NOTES_v2.0.0.md for complete details.

ci: add GitHub Actions workflow for Docker image build and push

Add automated workflow to build and publish Docker images to GHCR:
- Builds on push to master/main branches
- Builds on version tags (v*)
- Builds on pull requests (without pushing)
- Supports manual workflow dispatch

Features:
- Multi-platform support (linux/amd64)
- Automatic semantic versioning from git tags
- GitHub Actions cache for faster builds
- Build attestation for supply chain security
- Images pushed to ghcr.io/netresearch/timetracker-ui

Tags generated:
- Branch name (e.g., master, main)
- PR number (e.g., pr-123)
- Semantic versions (e.g., v1.0.0, v1.0, v1)
- Git SHA (e.g., master-abc1234)
- 'latest' for default branch

chore(dev): add development tooling and automation

- Add .nvmrc to enforce Node 14 requirement
- Add .prettierrc for consistent code formatting
- Add setup-dev.sh for automated project setup
  - Validates Node version
  - Installs dependencies
  - Creates config.json from template
  - Provides clear instructions

Improves developer onboarding and prevents Node version issues.

Updated package.json

Correct description until end of month