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/features/lobby/HierarchyItemMenu.tsx

@@ -18,6 +18,7 @@ import {
 import { HierarchyItem } from '../../hooks/useSpaceHierarchy';
 import { useMatrixClient } from '../../hooks/useMatrixClient';
 import { MSpaceChildContent, StateEvent } from '../../../types/matrix/room';
+import { sendStateEvent } from '../../utils/room';
 import { AsyncStatus, useAsyncCallback } from '../../hooks/useAsyncCallback';
 import { UseStateProvider } from '../../components/UseStateProvider';
 import { LeaveSpacePrompt } from '../../components/leave-space-prompt';
@@ -48,7 +49,7 @@ function SuggestMenuItem({
   const [toggleState, handleToggleSuggested] = useAsyncCallback(
     useCallback(() => {
       const newContent: MSpaceChildContent = { ...content, suggested: !content.suggested };
-      return mx.sendStateEvent(parentId, StateEvent.SpaceChild as any, newContent, roomId);
+      return sendStateEvent(mx, parentId, StateEvent.SpaceChild, newContent, roomId);
     }, [mx, parentId, roomId, content]),
   );
 
@@ -85,7 +86,7 @@ function RemoveMenuItem({
 
   const [removeState, handleRemove] = useAsyncCallback(
     useCallback(
-      () => mx.sendStateEvent(parentId, StateEvent.SpaceChild as any, {}, roomId),
+      () => sendStateEvent(mx, parentId, StateEvent.SpaceChild, {}, roomId),
       [mx, parentId, roomId],
     ),
   );