fix: resolve conflict markers and remove legacy code after branch consolidation
- Remove conflict markers from 19 files that were accidentally committed
during merge resolutions (keeping HEAD versions)
- Remove legacy root-level code (core.go, main.go, config/, crypt/,
display/, filesystem/, workspace/, docs/*.go, cmd/app/) from old
architecture predating pkg/ restructure
- Remove duplicate pkg/config/loader.go (Load/Save already in config.go)
- Fix import alias in cmd_apply.go (errors -> core)
Co-Authored-By: Virgil <virgil@lethean.io>