Complete piglet implementation with animations and effects

- Implement complete animation system with 20+ motion effects
- Add 18+ easing functions (quad, cubic, elastic, back, bounce)
- Implement color system with palette and gradient support
- Add parser for durations, colors, and CSS gradients
- Create comprehensive test suite (14 tests passing)
- Add linting and formatting with clippy/rustfmt
- Support for figlet integration with custom fonts
- Terminal rendering with crossterm
- Fix all clippy warnings and lint issues

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/color/gradient.rs

@@ -1,7 +1,8 @@
-use crate::parser::gradient::Gradient;
 use crate::parser::color::Color;
+use crate::parser::gradient::Gradient;
 use anyhow::Result;
 
+#[derive(Debug, Clone)]
 pub struct GradientEngine {
     gradient: Gradient,
 }
@@ -10,17 +11,17 @@ impl GradientEngine {
     pub fn new(gradient: Gradient) -> Self {
         Self { gradient }
     }
-    
+
     pub fn from_string(gradient_str: &str) -> Result<Self> {
         let gradient = Gradient::parse(gradient_str)?;
         Ok(Self::new(gradient))
     }
-    
+
     pub fn color_at(&self, t: f64) -> Color {
         self.gradient.color_at(t)
     }
-    
+
     pub fn colors(&self, steps: usize) -> Vec<Color> {
         self.gradient.colors(steps)
     }
-}
+}