#3813 chore(deps): remove debounce dependency

debounce was only used once, in setup-hot-reloading.ts, to batch file changes into a single reload event for the preview app. A setTimeout/clearTimeout pair does the same job, so this removes the dependency.

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Summary by cubic

Removes the debounce dependency by replacing its only usage in setup-hot-reloading.ts with a setTimeout/clearTimeout pair. The hot-reload batching behavior—waiting 150ms for file changes before sending a single reload event—is unchanged. The dependency is also dropped from package.json and pnpm-lock.yaml, with a changeset released as a react-email patch.