Proposal: `vp run --watch` (re-run tasks on changes) leveraging existing tracking/caching

[ubugeeei]

Problem

In monorepos, a common workflow is “run lint/tests/build continuously as files change.”
mise provides mise watch as a first-class feature. Vite Tasks already has planning/caching and (in the broader Vite+ ecosystem) file dependency ideas, so watch-mode could be especially powerful.

Evidence (primary)

• Vite Tasks CLI currently exposes run and cache ... commands; no watch flag/subcommand is visible in the CLI definition.

Proposed behavior (Unspecified)

• vp run --watch <task> or vp watch <task> (syntax unspecified)
• On file changes, rerun the task (possibly only the necessary affected subtasks)
• Provide debounce/throttle config (unspecified)

Backward compatibility

• Additive feature; no change to current behavior unless used.

Minimal implementation suggestion (MVP)

• Start with a basic file watcher over a configured path set.
• Iterate to use tracked inputs/outputs to narrow watch scope, and integrate with caching.