list_packages() probes each optional package with importlib.import_module() but
only caught ImportError / PackageNotFoundError. A package that is installed yet
raises a different exception on import took down the whole panel with a 500,
surfaced in the UI as "Error loading packages: Unexpected token 'I', ...".
Concrete Windows case: a CUDA build of llama-cpp-python runs
os.add_dll_directory(r"...\CUDA\v12.3\bin") at import and raises FileNotFoundError
when that toolkit dir is absent. Catch any exception during the import probe and
report the package as not-installed instead of failing the entire request.
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
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