I've added JSDoc comments to interface hooks and utils.

This change introduces JSDoc-style comments to several TypeScript files within your `src/interface` directory to improve code understanding and maintainability, focusing on hooks and utility functions.

- `src/interface/hooks/BackgroundDataLoader.ts`: I added comments to all exported functions and the `BackgroundDB` interface, detailing IndexedDB interactions for background image storage.
- `src/interface/hooks/SettingsPopup.ts`: I documented the public methods of the `SettingsPopup` singleton, which handles event notifications for settings popup closures.
- `src/interface/utils/themeImageHandlers.ts`: I added comments to all exported functions, explaining their roles in managing images within custom themes (uploading, removing, etc.).
- `src/interface/hooks/BackgroundUpdates.ts`: I documented the `BackgroundUpdates` singleton class and its methods, used for broadcasting generic background update events.
- `src/interface/hooks/ThemeUpdates.ts`: I documented the `ThemeUpdates` singleton class and its methods, responsible for broadcasting theme-related update events.

src/interface/utils/themeImageHandlers.ts

@@ -1,9 +1,27 @@
 import type { LoadedCustomTheme } from "@/types/CustomThemes";
 
+/**
+ * Generates a random 9-character alphanumeric string to be used as a unique ID for images.
+ * This helps in identifying and managing custom images within a theme.
+ *
+ * @returns {string} A randomly generated unique ID string.
+ */
 export function generateImageId(): string {
   return Math.random().toString(36).substr(2, 9);
 }
 
+/**
+ * Handles the upload of a new custom image from a file input event.
+ * If a file is selected, it reads the file using FileReader, converts it to a Blob,
+ * generates a unique ID and a default variable name for it, and then adds this new image
+ * to the `CustomImages` array within the provided `theme` object.
+ *
+ * @param {Event} event The file input change event, typically from an `<input type="file">` element.
+ * @param {LoadedCustomTheme} theme The current theme object to which the new image will be added.
+ * @returns {Promise<LoadedCustomTheme> | LoadedCustomTheme} A Promise that resolves with the updated theme object
+ *                                                          containing the new image if a file was processed.
+ *                                                          Returns the original theme object synchronously if no file was selected.
+ */
 export function handleImageUpload(
   event: Event,
   theme: LoadedCustomTheme,
@@ -34,6 +52,16 @@ export function handleImageUpload(
   return theme;
 }
 
+/**
+ * Removes a custom image from the theme based on its ID.
+ * It filters out the image with the specified `imageId` from the `CustomImages` array
+ * in the `theme` object.
+ *
+ * @param {string} imageId The unique ID of the custom image to be removed.
+ * @param {LoadedCustomTheme} theme The current theme object from which the image will be removed.
+ * @returns {LoadedCustomTheme} A new theme object with the specified image removed from its `CustomImages` array.
+ *                              This function is synchronous.
+ */
 export function handleRemoveImage(
   imageId: string,
   theme: LoadedCustomTheme,
@@ -44,6 +72,17 @@ export function handleRemoveImage(
   } as LoadedCustomTheme;
 }
 
+/**
+ * Updates the CSS variable name associated with a specific custom image in the theme.
+ * It finds the image by `imageId` in the `CustomImages` array of the `theme` object
+ * and updates its `variableName` property.
+ *
+ * @param {string} imageId The unique ID of the custom image whose variable name is to be updated.
+ * @param {string} variableName The new CSS variable name to assign to the image.
+ * @param {LoadedCustomTheme} theme The current theme object containing the image to be updated.
+ * @returns {LoadedCustomTheme} A new theme object with the updated image variable name.
+ *                              This function is synchronous.
+ */
 export function handleImageVariableChange(
   imageId: string,
   variableName: string,
@@ -57,6 +96,17 @@ export function handleImageVariableChange(
   } as LoadedCustomTheme;
 }
 
+/**
+ * Handles the upload of a cover image for the theme from a file input event.
+ * If a file is selected, it reads the file using FileReader, converts it to a Blob,
+ * and then updates the `coverImage` property of the provided `theme` object with this new blob.
+ *
+ * @param {Event} event The file input change event, typically from an `<input type="file">` element.
+ * @param {LoadedCustomTheme} theme The current theme object whose cover image will be updated.
+ * @returns {Promise<LoadedCustomTheme>} A Promise that resolves with the updated theme object
+ *                                       containing the new cover image if a file was processed.
+ *                                       Returns a Promise resolving with the original theme object if no file was selected.
+ */
 export function handleCoverImageUpload(
   event: Event,
   theme: LoadedCustomTheme,