Use an alternate border for custom cards; move the images from the repository to external

TableturfBattleClient/index.html

@@ -510,7 +510,7 @@
 						Import from screenshots
 					</label>
 					<section id="deckImportScreenshotSection">
-						<input type="file" id="deckImportFileBox" accept="image/png,image/jpeg,image/webp,image/bmp" multiple autocomplete="off"/>
+						<input type="file" id="deckImportFileBox" accept="image/*" multiple autocomplete="off"/>
 						<div>
 							<button type="button" id="deckImportScreenshotInstructionsButton">Show instructions</button>
 							<div id="deckImportScreenshotInstructions" hidden>

TableturfBattleClient/src/CardDisplay.ts

@@ -33,7 +33,7 @@ class CardDisplay implements ICardElement {
 		// Background
 		const image = document.createElementNS('http://www.w3.org/2000/svg', 'image');
 		image.setAttribute('class', 'cardDisplayBackground');
-		image.setAttribute('href', `assets/CardBackground-${card.rarity}-${level > 0 ? '1' : '0'}.webp`);
+		image.setAttribute('href', `assets/external/CardBackground${card.isCustom ? '-custom' : ''}-${card.rarity}-${level > 0 ? '1' : '0'}.webp`);
 		image.setAttribute('width', '100%');
 		image.setAttribute('height', '100%');
 		svg.appendChild(image);