PR #52 merged: chore: clean up docs and remove dead migration code

Summary

• Remove all references to non-existent coolify_resources table
• Remove dead migration code from InstallCommand and ServiceProvider
• Update docs to reflect environment-based resource fetching (not git repo matching)
• Rewrite CHANGELOG with accurate v3.0.0 and [Unreleased] sections
• Document environment switcher functionality in multi-app.md

Test plan

• composer test passes (230 tests)
• composer lint passes