Animate follow icon rotation in Jetcaster (#1603)

### Overview

This PR adds a small rotation animation to the "Follow" icon in the
Jetcaster app to improve visual feedback when toggling follow/unfollow.
This implements the TODO found in FollowButton.kt: `// TODO: think about
animating these icons`

### What Changed

- Added an `animateFloatAsState` to animate icon rotation from 0f to
360f when `isFollowed` changes
- Applied `Modifier.rotate()` to the Icon based on the animated value

### Why

This small UX enhancement helps to make the follow action feel more
responsive and polished visually for users.

### How it looks like (example screen recording)


![Screen_recording_20250818_202230](https://github.com/user-attachments/assets/0ad3d09a-decf-479b-8c53-2672db335894)

Let me know if any adjustments are needed. 🙂

Author: riggaroo

Jetcaster/mobile/src/main/java/com/example/jetcaster/util/Buttons.kt

@@ -16,6 +16,10 @@
 
 package com.example.jetcaster.util
 
+import androidx.compose.animation.core.animateFloat
+import androidx.compose.animation.core.snap
+import androidx.compose.animation.core.spring
+import androidx.compose.animation.core.updateTransition
 import androidx.compose.foundation.shape.CircleShape
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material3.ExperimentalMaterial3ExpressiveApi
@@ -25,7 +29,9 @@ import androidx.compose.material3.IconToggleButtonColors
 import androidx.compose.material3.IconToggleButtonShapes
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.rotate
 import androidx.compose.ui.res.painterResource
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.unit.dp
@@ -52,8 +58,25 @@ fun ToggleFollowPodcastIconButton(isFollowed: Boolean, onClick: () -> Unit, modi
             checkedShape = CircleShape,
         ),
     ) {
+        val transition = updateTransition(targetState = isFollowed, label = "FollowToggle")
+        val iconRotation by transition.animateFloat(
+            label = "IconRotation",
+            transitionSpec = {
+                if (initialState == targetState) {
+                    snap()
+                } else {
+                    spring(
+                        dampingRatio = 0.6f,
+                        stiffness = 200f,
+                    )
+                }
+            },
+        ) { followed ->
+            if (followed) 360f else 0f
+        }
+
         Icon(
-            // TODO: think about animating these icons
+            // Animated rotation when follow state changes
             painter = when {
                 isFollowed -> painterResource(id = R.drawable.ic_check)
                 else -> painterResource(id = R.drawable.ic_add)
@@ -62,6 +85,7 @@ fun ToggleFollowPodcastIconButton(isFollowed: Boolean, onClick: () -> Unit, modi
                 isFollowed -> stringResource(R.string.cd_following)
                 else -> stringResource(R.string.cd_not_following)
             },
+            modifier = Modifier.rotate(iconRotation),
         )
     }
 }