[Glitch] Upgrade to ESLint v9 flat config

Port e8270e2807 to glitch-soc

Co-authored-by: Nick Schonning <nschonni@gmail.com>
Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/components/router.tsx

@@ -1,5 +1,5 @@
 import type { PropsWithChildren } from 'react';
-import React from 'react';
+import type React from 'react';
 
 import { Router as OriginalRouter, useHistory } from 'react-router';