- Replace cmd/stubs.go dorksCmd stub with full command tree
- Add cmd/dorks.go with list, info, export subcommands
- Wire Registry + custom_dorks merge for list/export
- Bind GITHUB_TOKEN env var via viper for downstream run
Satisfies part of DORK-03 (list/info/export) and DORK-04 (source/category
filtering). run/add/delete land in Task 2.
