refactor(DP15): centralize sendStateEvent as-any cast in typed helper

Add a typed `sendStateEvent(mx, roomId, eventType, content, stateKey?)`
helper in utils/room.ts that mirrors the DP16 account-data helper pattern.
The SDK's typed `sendStateEvent` overload rejects the fork's custom
`StateEvent` enum values, so every call site cast arg 2 to `any` (which
also collapsed the content type). The single `as any` cast now lives inside
the helper; a generic `content: T extends object` keeps each call site's
content type checked.

Route all 32 `mx.sendStateEvent(..., StateEvent.X as any, ...)` casts across
20 files through the helper. The 2 dynamic-string casts in developer-tools
(SendRoomEvent, StateEventEditor) pass a runtime string, not an enum value,
so they stay as-is.

No behavior change.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/components/create-room/utils.ts

@@ -8,6 +8,7 @@ import {
 } from 'matrix-js-sdk';
 import { RoomJoinRulesEventContent } from 'matrix-js-sdk/lib/types';
 import { RoomType, StateEvent } from '../../../types/matrix/room';
+import { sendStateEvent } from '../../utils/room';
 import { getViaServers } from '../../plugins/via-servers';
 import { getMxIdServer } from '../../utils/matrix';
 import { CreateRoomAccess } from './types';
@@ -150,9 +151,10 @@ export const createRoom = async (mx: MatrixClient, data: CreateRoomData): Promis
   const result = await mx.createRoom(options);
 
   if (data.parent) {
-    await mx.sendStateEvent(
+    await sendStateEvent(
+      mx,
       data.parent.roomId,
-      StateEvent.SpaceChild as any,
+      StateEvent.SpaceChild,
       {
         auto_join: false,
         suggested: false,