Needs System & Autonomous AI

Implement a needs system in Rust with four needs (hunger, energy, social, fun) that decay over time.

Define a mood score in Rust computed as a weighted function of current need levels.

Create a game clock in Rust with pause, normal, and fast-forward speeds that drives need decay.

Create four need-fulfilling interactions (e.g., eat, sleep) that modify need values in the Rust backend.

Build a simple autonomous AI in Rust that selects a need-fulfilling action based on the character's lowest need.

Implement an autonomy toggle in the UI to switch between player-controlled and AI-controlled modes.