[feature]: loopflow new <name> — scaffold a single blank loop

[faisalishfaq2005]

What problem would this solve?

loopflow init copies all three starter templates at once, but there's no way to create one fresh, empty loop to build from. You
▎ either overwrite the starters or hand-write a YAML file from scratch.

Proposed solution

Add a loopflow new command that writes a minimal, commented .loopflow/loops/.yaml with one work step and one gate
▎ step, and refuses to overwrite an existing file without --force.
▎
▎ Where to start:
▎ - Add a handler in src/commands/ (mirror the --force / file-exists logic in init.ts).
▎ - Wire the command into src/cli.ts next to the other program.command(...) blocks.
▎ - Add a test.
▎
▎ New to the project? npm install && npm test runs in under a second — see CONTRIBUTING.md.

Alternatives considered

No response

Scope

• I've checked this isn't already on the roadmap in the README.
• This can't reasonably be expressed as a loop instead of engine code.