[WIP] - 3.0: Remove complex custom Reactive Systems and standardize the public API to make it easy to maintain with clear responsibilities and logic. (Goal: Single-file pure code under 1000 lines)

[WIP] - 3.0: Remove complex custom Reactive Systems and standardize the public API to make it easy to maintain with clear responsibilities and logic. (Goal: Single-file pure code under 1000 lines) #945