What are animation curves in Flutter, such as Curves.easeIn or Curves.bounceOut, and how do they let you control the specific pacing and feel of an animation rather than it always simply moving at a perfectly constant, linear speed?

An animation curve defines exactly how an animation's progress value actually changes over time relative to its overall elapsed duration, letting you create effects such as an animation that starts out relatively slowly and then noticeably accelerates, one that overshoots its final target slightly before gently settling back into place, or one that produces a distinctly bouncy, playful feeling, rather than the animation simply always moving forward at one perfectly constant, linear speed throughout its entire duration, and thoughtfully choosing an appropriate curve for a specific animation can meaningfully improve how genuinely polished and natural that resulting animation actually feels to a user.

final curvedAnimation = CurvedAnimation(
  parent: controller,
  curve: Curves.easeInOut,
);