Ruby 3 modernization: fix legacy, HTTPS/watch, public_url, subfolder support, CI, tests

[hennrunnel]

Ruby 3 modernization: fix legacy, HTTPS/watch, public_url, subfolder support, CI, tests

• Upgrade voog-kit to Ruby 3.x (drop 2.7), modernize deps, and resolve longstanding issues. Add tests and manual CI matrix.

Changes

• Require Ruby >= 3.0; update gemspec dependencies
• CLI: subfolder root detection; no-color fallback; homepage link fix
• Assets: download via public_url; text/binary handling; filename slash-safe mapping (with reverse on upload)
• Manifest: singular asset kinds; preserve layout titles; auto-add missing files on push
• Error layouts: infer content_type; auto-create 404 on first push if missing
• Watch: HTTPS propagation verified; Windows note added (may use polling)
• Docs: Ruby 3.x, HTTPS examples, subfolder note, updated links
• CI: manual workflow_dispatch; matrix for Ubuntu/macOS/Windows; runs rspec + CLI smoke
• Tests: RSpec suite included; all green locally

Fixed issues

• Fixes Use only public_url when downloading layout assets #45 Use public_url for asset downloads
• Fixes "kit watch" giving error with https:// #52 HTTPS handling in watch
• Fixes custom 404 layouts are not created automatically on push #51 Auto-create custom 404 on first push
• Fixes Improve Kit's output to work on both dark and light backgrounds #50 Color output readable on dark/light
• Fixes kit should work in subfolders (images/, javascripts/ etc.) #39 Support running in subfolders
• Fixes kit manifest sets assets' kind attribute incorrectly #42 Manifest asset “kind” singular
• Fixes Add command to check for updates to the Voog-kit gem itself #37 Add command to check for voog-kit updates
• Fixes Filenames are not properly escaped when comparing them to local/remote counterparts #49 Properly handle filenames with slashes
• Fixes "kit init new" doesn't properly fallback to the boilerplate URL #46 Improve ‘kit init new’ fallback
• Fixes when creating new layout files, underscores are converted into spaces when generating the default layout_names #47 Preserve underscores in default layout titles

Testing

• RSpec: 70 examples passing locally
• CI (manual): builds on Ubuntu/macOS/Windows; runs rspec and CLI smoke

Notes

• Breaking: Ruby 3.x required. Proposed version: 0.6.0
• Windows watch may fall back to polling if native adapters unavailable