This PR fixes #831 by moving the copyPublicDir call inside the buildAll function. As a result, files from the public directory are now also copied when debouncedBuildAll is triggered (e.g., in watch mode).

This introduces a potential breaking change:

Before:

• if onSuccess was a function, it was always called before copyPublicDir was even invoked.
• if onSuccess was a string, both the copy and the shell command were started simultaneously, leading to race conditions. In most cases, the copy finished first, but behavior was unreliable

After this change:

• onSuccess is always called after copyPublicDir completes — ensuring the build (including public files) is fully ready before executing any post-build logic.

Potential improvements:

• optimize by running copyPublicDir inside debouncedBuildAll only when options.clean is true. However, this may not be worth the added complexity: most public directories are probably small and debouncedBuildAll is already throttled. The current implementation is simpler and more predictable, which may outweigh this optimization.
• tests (requires test for watch mode)