Create a simple interactive coloring application that allows users to choose from a selection of hand-drawn images and color them using a variety of vibrant colors.

First Screen
1. Display Thumbnails: Show thumbnails of the provided images for easy navigation:
   - Image 1: [Zoo Animals](https://img.freepik.com/free-vector/hand-drawn-zoo-animals-illustration_23-2151199715.jpg)
   - Image 2: [Second Zoo Animals](https://img.freepik.com/free-vector/hand-drawn-zoo-animals-illustration_23-2151199718.jpg)
   - Image 3: [Lion & Giraffe](https://img.freepik.com/premium-vector/lion-giraffe-hand-drawn_185029-508.jpg)
   - Image 4: [Owl Outline](https://img.freepik.com/free-vector/hand-drawn-owl-outline-illustration_23-2149277379.jpg)
   - Image 5: [Fox Outline](https://img.freepik.com/free-vector/hand-drawn-fox-outline-illustration_23-2149272718.jpg)
   - Image 6: [Lion Outline](https://img.freepik.com/free-vector/hand-drawn-lion-outline-illustration_23-2149285355.jpg)
   - Image 7: [Penguin Outline](https://img.freepik.com/free-vector/hand-drawn-penguin-outline-illustration_23-2150582038.jpg)
   - Image 8: [Giraffe Doodle](https://img.freepik.com/free-vector/animal-doodle-outline-cute-giraffe_1308-81895.jpg)

Thumbnails should be small yet clickable to navigate comfortably to the coloring page.

After Selecting an Image
2. Image Display: Show the selected image in full-screen vertically centered.

3. Functional Buttons:
   - Back Button (top-left): Prompts with confirmation dialog — "Are you sure you want to go back? Any unsaved changes will be lost.", then navigates back to thumbnail screen.
   - Save Button (top-left): Saves the current colored image as a PNG file.
   - Color Palette (top-right): Displays a large red circle indicating the current color; clicking opens a fullscreen color palette with 24 vibrant options.

Coloring Interaction
4. Fill Areas: Enable users to fill image areas with the selected color by detecting image boundaries. On tapping or clicking within a defined boundary, fill the area with the current selected color.

Color choices should provide an engaging user experience with rich colors and straightforward interaction to encourage creativity.

Create a simple interactive coloring application:
First screen:
- Display thumbnails of the provided images:
  1. https://img.freepik.com/free-vector/hand-drawn-zoo-animals-illustration_23-2151199715.jpg
  2. https://img.freepik.com/free-vector/hand-drawn-zoo-animals-illustration_23-2151199718.jpg
  3. https://img.freepik.com/premium-vector/lion-giraffe-hand-drawn_185029-508.jpg
  4. https://img.freepik.com/free-vector/hand-drawn-owl-outline-illustration_23-2149277379.jpg
  5. https://img.freepik.com/free-vector/hand-drawn-fox-outline-illustration_23-2149272718.jpg
  6. https://img.freepik.com/free-vector/hand-drawn-lion-outline-illustration_23-2149285355.jpg
  7. https://img.freepik.com/free-vector/hand-drawn-penguin-outline-illustration_23-2150582038.jpg
  8. https://img.freepik.com/free-vector/animal-doodle-outline-cute-giraffe_1308-81895.jpg

- Thumbnails should be small and easy to navigate.

After selecting an image:
- Display the chosen image full-screen vertically.
- Top-left corner:
  - "Back" button: returns to image selection after confirmation dialog.
  - "Save" button: downloads the colored image.
- Top-right corner:
  - Large red circle indicating the current selected color (default is bright blue).
  - On clicking the circle, display a fullscreen palette with 24 vibrant color options arranged as small circles. After selecting a color, close the palette.

Coloring interaction:
- Detect boundaries of image areas.
- On click/tap within boundaries, fill the area with the selected color.

Q: What should the confirmation dialog say when returning to image selection?
A: Are you sure you want to go back? Any unsaved changes will be lost.

Q: What should happen when the 'Save' button is clicked?
A: Just save it in PNG format.