fix(cookbook): don't 500 the packages panel when an optional package crashes on import (#2618)

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>

routes/shell_routes.py

@@ -1209,6 +1209,12 @@ def setup_shell_routes() -> APIRouter:
                     pkg["installed"] = False
                 except importlib_metadata.PackageNotFoundError:
                     pkg["installed"] = False
+                except Exception:
+                    # Installed but crashes on import — e.g. a CUDA build of
+                    # llama-cpp-python raising FileNotFoundError when the CUDA
+                    # toolkit dir is absent. One broken optional package must not
+                    # 500 the entire packages panel; report it as not usable.
+                    pkg["installed"] = False
 
             if pkg.get("installed"):
                 update_status = _package_pip_update_status(pkg, probe)