Updating Preact JS Submodule and preact_signals Package

This guide details the systematic process for updating the pinned Preact.js Signals JS/TS git submodule (third_party/preactjs_signals) and porting its structural updates, algorithmic changes, and optimizations into the Dart preact_signals package.

1. Upstream Submodule Management

The upstream JavaScript/TypeScript implementation is tracked via a Git submodule located at third_party/preactjs_signals.

A. Initializing and Synchronizing the Submodule

If the submodule is not initialized, run:

git submodule update --init --recursive