Support alternative state mutation and comparison strategies (e.g. Immutable.js, plain JS)

[flexsurfer]

Description:

The current implementation uses Immer.js for state mutation and fast-deep-equal for structural comparison of reaction dependencies.

We want to make these components pluggable to support alternative approaches such as:

• Pure JavaScript (without Immer)
• Immutable.js
• Custom strategies (e.g. using different equality functions or immutable data libs)

Tasks:

• Abstract the mutation logic behind a consistent API (e.g. createStateProxy())
• Abstract equality check logic (e.g. areValuesEqual(a, b))
• Add configuration options or adapters for different strategies
• Provide examples or tests for each approach