fix(frontend): point remaining GitHub repo links at this fork

The sidebar's version badge and the subscription-templates docs link
still hardcoded MHSanaei/3x-ui. install.sh and every README already
point at Kuzz007/3x-ui; these were the last two functional (non-credit)
repo links left pointing upstream. DONATE_URL/DOCS_URL intentionally
left alone -- those point at the original author's own donation page
and docs site, which is deliberate per this fork's existing convention
of crediting/linking upstream for general (non-fork-specific) info.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

frontend/src/pages/settings/SubscriptionGeneralTab.tsx

@@ -128,7 +128,7 @@ export default function SubscriptionGeneralTab({ allSetting, updateSetting }: Su
                 <>
                   {t('pages.settings.subThemeDirDesc')}{' '}
                   <a
-                    href="https://github.com/MHSanaei/3x-ui/blob/main/docs/custom-subscription-templates.md"
+                    href="https://github.com/Kuzz007/3x-ui/blob/main/docs/custom-subscription-templates.md"
                     target="_blank"
                     rel="noopener noreferrer"
                   >