Fix CustomCollectionCallbacks authorizePredicate type parameter

Changed `keyof TParam & string` to `TParam` in authorize callbacks.
Since TParam is now `string` instead of `Record<string, string>`,
`keyof TParam` would incorrectly resolve to string method names
like "toString", "charAt", etc.

This fixes type checking errors introduced when refactoring collection
dispatcher types from Record-based to string-based parameters.

Author: dahlia

packages/fedify/src/federation/builder.ts

@@ -1520,7 +1520,7 @@ export class FederationBuilderImpl<TContextData>
       authorize(
         predicate: ObjectAuthorizePredicate<
           TContextData,
-          keyof TParam & string
+          TParam
         >,
       ) {
         callbacks.authorizePredicate = predicate;

packages/fedify/src/federation/handler.ts

@@ -912,7 +912,7 @@ export interface CustomCollectionCallbacks<
    */
   authorizePredicate?: ObjectAuthorizePredicate<
     TContextData,
-    keyof TParam & string
+    TParam
   >;
 }