docs: clean up imgcli scaffold

[jmgilman]

Summary

• move the initial design into the docs tree
• replace template placeholders with imgcli-specific docs, metadata, and repo settings
• add Apache-2.0/MIT dual licensing
• tighten Moon docs CI to typecheck and build only

Validation

• npm --prefix docs run typecheck
• npm --prefix docs run build
• moon ci --summary minimal
• uv run scripts/configure_github_repo.py apply --repo meigma/imgcli
• uv run scripts/configure_github_repo.py plan --repo meigma/imgcli
• git diff --check