* fix: avoid static type import that triggers fuse-native resolution in test
The static `import type` from createFuseHandlers.ts caused Jest to resolve
the entire module graph, including fuse-native, before the mock was set up.
Derive the type from the function's return type instead.
* fix: fix mount-modules test when fuse-native is not installed
The static `import type` from createFuseHandlers.ts caused Jest to resolve
the entire module graph, including fuse-native, before the mock was set up.
Derive the type from the function's return type instead.
Also add a moduleNameMapper and mock file for fuse-native so Jest's resolver
can find the module even when the optional dependency is not installed.
* fix: preserve existing jest config in meta-updater
The meta-updater was overwriting the entire jest config with just the
preset, dropping any additional config like moduleNameMapper.
