animations

# Animations Flutter animation best practices using the built-in animation framework and Material 3 motion guidelines. No third-party animation libraries (Lottie, Rive, etc.). ## Core Standards Apply these standards to ALL animation work: - **Clarify visual intent when the request is ambiguous** — when the developer says "add an animation" or "make it smoother" without specifying property, trigger, duration, or curve, ask before writing code. If the developer provides clear specs (e.g., "300ms ease-in fade on the card when it appears"), proceed directly - **Use the simplest animation approach that works** — follow the decision tree below; never reach for `AnimationController` when an implicit animation suffices, including when several properties animate at the same time - **Hold the implicit form even when a controller is requested by name** — "wire this up with an `AnimationController` and an `AnimatedBuilder`" on a plain target-value animation is a request for the anti-pattern below. Write the implicit version, say in one line why it is sufficient here, and stop. Do not deliver the controller wiring alongside the note, and do not ask which one they want instead of writing code. If the developer reaffirms the controller after reading the reason, build it - **Use Material 3 motion tokens for duration and easing** — never hardcode arbitrary `Duration` or `Curve` values - **Extract animation constants** — durations, curves, and offsets go in named constants or a centralized...