chore: auto-fix Biome formatting and configure lint rules

Run biome check --write --unsafe to fix tabs, import ordering, and
non-null assertions across entire codebase. Disable a11y rules not
applicable to this single-user app. Exclude auto-generated routeTree.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/client/components/ExternalLinkDialog.tsx

@@ -37,9 +37,7 @@ export function ExternalLinkDialog() {
 				<h3 className="text-lg font-semibold text-gray-900 mb-2">
 					You are about to leave GearBox
 				</h3>
-				<p className="text-sm text-gray-600 mb-1">
-					You will be redirected to:
-				</p>
+				<p className="text-sm text-gray-600 mb-1">You will be redirected to:</p>
 				<p className="text-sm text-blue-600 break-all mb-6">
 					{externalLinkUrl}
 				</p>