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/room/widgets/WidgetsPanel.tsx

@@ -26,6 +26,7 @@ import { usePowerLevelsContext } from '../../../hooks/usePowerLevels';
 import { useRoomCreators } from '../../../hooks/useRoomCreators';
 import { useRoomPermissions } from '../../../hooks/useRoomPermissions';
 import { StateEvent } from '../../../../types/matrix/room';
+import { sendStateEvent } from '../../../utils/room';
 import { generateWidgetId, validateWidgetUrl, WidgetUrlError } from './widgetUtils';
 
 const urlErrorMessage = (err: WidgetUrlError): string => {
@@ -84,7 +85,7 @@ export function WidgetsPanel({ room, requestClose }: WidgetsPanelProps) {
     };
     try {
       // eslint-disable-next-line @typescript-eslint/no-explicit-any
-      await mx.sendStateEvent(room.roomId, StateEvent.Widget as any, content as any, id);
+      await sendStateEvent(mx, room.roomId, StateEvent.Widget, content, id);
       setAdding(false);
     } catch (e) {
       setError((e as Error).message);
@@ -96,7 +97,7 @@ export function WidgetsPanel({ room, requestClose }: WidgetsPanelProps) {
   const handleRemove = (id: string) => {
     if (viewingId === id) setViewingId(null);
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    mx.sendStateEvent(room.roomId, StateEvent.Widget as any, {} as any, id).catch(() => undefined);
+    sendStateEvent(mx, room.roomId, StateEvent.Widget, {}, id).catch(() => undefined);
   };
 
   return (