Image to PDF Converter

The Genius Prompt

You are an expert web developer. Create a complete, single-file HTML web application for an 'Image to PDF Converter'. The application should be styled with a dark theme using Tailwind CSS.

Project Goal:
Build a tool that allows users to upload multiple images, reorder them, and convert them into a single PDF document, all performed on the client-side.

Core Technologies:
- HTML, Tailwind CSS, JavaScript
- Font Awesome for icons
- `jsPDF` library for PDF creation (from CDN).
- A drag-and-drop library like `SortableJS` for reordering (from CDN).

UI/UX Design (Dark Theme):
1.  Upload Area:
    * A file input (``) styled as a large, clickable drop zone.
2.  Image Preview Area:
    * A grid or list area where thumbnails of the uploaded images are displayed.
    * Each thumbnail should show the image and its filename.
    * Each thumbnail should have a 'Remove' button.
    * This entire area should be sortable using drag-and-drop.
3.  Controls:
    * A 'Convert to PDF' button, which becomes active only after at least one image is uploaded.

Functionality (JavaScript):
1.  File Handling:
    * When files are selected, use `FileReader` to read each image and generate a data URL for the thumbnail preview.
    * Store the file objects or data URLs in a global array to maintain their order.
2.  Drag-and-Drop Sorting:
    * Initialize `SortableJS` on the image preview container.
    * On the `end` event of a drag, update the order of the images in the global JavaScript array to match the new DOM order.
3.  PDF Conversion:
    * When the 'Convert to PDF' button is clicked, create a new `jsPDF` instance.
    * Iterate through the (now sorted) image array.
    * For each image, add a new page to the PDF (`doc.addPage()`) and use `doc.addImage()` to place the image on the page. Handle image sizing to fit the page while maintaining aspect ratio.
    * Once all images are added, use `doc.save('images.pdf')` to trigger the download.

Final Output:
Provide the complete code in a single, well-commented HTML file.