fix: restore rooms and DMs after React Router 7 upgrade

Stop double-encoding Matrix IDs in pathUtils, decode route params on read, fix millify CJS import, and read space children from currentState so channels and joins work again.

src/app/plugins/millify.ts

@@ -1,8 +1,8 @@
-import millifyPlugin from 'millify';
-import { MillifyOptions } from 'millify/dist/options';
+import { millify as millifyFn } from 'millify';
+import type { MillifyOptions } from 'millify/dist/options';
 
 export const millify = (count: number, options?: Partial<MillifyOptions>): string =>
-  millifyPlugin(count, {
+  millifyFn(count, {
     precision: 1,
     locales: [],
     ...options,