feat: add comprehensive GitHub Actions CI/CD workflows

[technusm1]

Summary

This PR adds a complete CI/CD setup for KiWings using GitHub Actions, including automated testing, releases, and dependency management.

Changes

Workflows Added

1. PR Checks (.github/workflows/pr-checks.yml)

• ✅ Validates PR titles using conventional commit format
• ✅ Builds the project on every PR
• ✅ Runs tests with graceful failure handling
• ✅ Caches Swift Package Manager dependencies

2. Release Workflow (.github/workflows/release.yml)

• ✅ Triggers on merges to main branch
• ✅ Uses semantic-release for automatic versioning
• ✅ Builds Release configuration
• ✅ Creates DMG installer with Applications symlink
• ✅ Generates SHA-256 checksums
• ✅ Creates GitHub releases with proper tags and notes
• ✅ Updates CHANGELOG.md automatically

3. Dependabot (.github/dependabot.yml)

• ✅ Weekly updates for GitHub Actions
• ✅ Weekly updates for Swift packages (grouped)
• ✅ Weekly updates for npm dependencies
• ✅ Uses conventional commit messages

4. Semantic Release Config (.releaserc.json)

• ✅ Conventional commit-based versioning
• ✅ Automatic changelog generation
• ✅ Updates Info.plist with version numbers
• ✅ Publishes releases to GitHub

Configuration Details

Runner: macOS 14 with Xcode 15.4

• Provides backward compatibility (supports Xcode 15.0.1 through 16.2)
• Stable and widely used
• Easy upgrade path to macOS 15 when needed

Export Options: Unsigned builds for now (can be signed later)

Commit Message Format

For the release workflow to function properly, use conventional commit format:

• feat: new feature → minor version bump (0.x.0)
• fix: bug fix → patch version bump (0.0.x)
• feat!: breaking change → major version bump (x.0.0)
• docs: documentation → patch version bump
• chore: maintenance → no release

Test Plan

• Created all workflow files
• Configured Dependabot
• Set up semantic-release
• Verify PR checks run on this PR
• After merge, verify release workflow creates DMG

Notes

• First merge to main will create initial release (likely v1.0.0)
• Dependabot will start creating PRs for dependency updates weekly
• All releases will include DMG + SHA-256 checksum + auto-generated changelog