feat: allow hosting hash-based apps from html files other than index.html

Fixes #14824.

Author: lishaduck

.changeset/upset-parents-sniff.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': minor
+---
+
+feat: allow hosting hash-based apps from non-index.html files

packages/kit/src/runtime/client/utils.js

@@ -317,12 +317,11 @@ export function is_external_url(url, base, hash_routing) {
 	}
 
 	if (hash_routing) {
-		if (url.pathname === base + '/' || url.pathname === base + '/index.html') {
-			return false;
-		}
-
-		// be lenient if serving from filesystem
-		if (url.protocol === 'file:' && url.pathname.replace(/\/[^/]+\.html?$/, '') === base) {
+		if (
+			url.pathname === base + '/' ||
+			url.pathname === base + '/index.html' ||
+			url.pathname.replace(/\/[^/]+\.html?$/, '') === base
+		) {
 			return false;
 		}