Add .venv, venv, __pycache__, .mypy_cache, .pytest_cache, build, and
.cache to the default ignored patterns for the skills watcher.
This prevents file descriptor exhaustion when a skill contains a Python
virtual environment with tens of thousands of files, which was causing
EBADF spawn errors on macOS.
Fixes#1056
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
On macOS, watching deep dependency trees can exhaust file descriptors and lead to spawn EBADF failures. The skills watcher only needs to observe skill changes, so ignore dotfiles, node_modules, and dist by default. Adds regression coverage.
