Add support for Flow

I love the idea of this project but we're using Flow, not TypeScript. It'd be great to have support for Flow as well, perhaps using something like pluggable adapters (Flow, TypeScript, or anything that can infer props from a component file).

Start by reviewing how the generator handles TypeScript React components and produces Jest snapshot-based tests. Determine the adapter boundary needed for Flow and other prop-inference sources, then verify that Flow component fixtures generate the expected snapshots without regressing existing TypeScript coverage.

Written by the indexing model from the issue text.