fix(theme): correctly normalize paths ending with "index" (#3544)

Co-authored-by: Divyansh Singh <40380293+brc-dd@users.noreply.github.com>

src/shared/shared.ts

@@ -16,8 +16,10 @@ export type {
 
 export const EXTERNAL_URL_RE = /^(?:[a-z]+:|\/\/)/i
 export const APPEARANCE_KEY = 'vitepress-theme-appearance'
-export const HASH_RE = /#.*$/
+
-export const EXT_RE = /(index)?\.(md|html)$/
+const HASH_RE = /#.*$/
+const HASH_OR_QUERY_RE = /[?#].*$/
+const INDEX_OR_EXT_RE = /(?:(^|\/)index)?\.(?:md|html)$/
 
 export const inBrowser = typeof document !== 'undefined'
 
@@ -60,8 +62,10 @@ export function isActive(
   return true
 }
 
-export function normalize(path: string): string {
+function normalize(path: string): string {
-  return decodeURI(path).replace(HASH_RE, '').replace(EXT_RE, '')
+  return decodeURI(path)
+    .replace(HASH_OR_QUERY_RE, '')
+    .replace(INDEX_OR_EXT_RE, '$1')
 }
 
 export function isExternal(path: string): boolean {