Implement /loop on top of a local recurring-task scheduler

[yaohaowei0914]

Background

/loop in the Bun reference is a bundled skill, but it only works because there is already a recurring-task scheduler underneath it.

Reference

• Entry: src/skills/bundled/loop.ts
• Related modules: ScheduleCronTool constants and gating.
• Behavior: parse interval syntax, convert to schedule form, create a recurring task, and immediately execute the prompt once.

Rust Gap

• No /loop command/skill today.
• No equivalent local scheduler tool chain yet.
• Suggested approach: build the recurring-task scheduler first, then expose /loop as the user-friendly wrapper.

Acceptance

• Support create/list/delete/trigger for local recurring tasks.
• /loop parses user input into a schedule and executes once immediately.
• Support both slash-command and plain-prompt payloads.
• Add scheduler and wrapper tests.