add Kong CLI skeleton with all command stubs
Parallel Kong implementation in pkg/cli/kong/ alongside the existing
Cobra CLI in pkg/cli/. Zero cross-imports between the two.
Includes:
- Root CLI struct with globals (--debug, --profile, --registry)
- Shared flag structs (BuildFlags, GPUFlags) replacing Cobra's addXxxFlag helpers
- Stub Run() methods for all 10 commands matching the Cobra tree
- Entry point at cmd/cog-kong/main.go
- Both binaries build cleanly side by side
