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/utils/room.ts

@@ -8,6 +8,7 @@ import {
   IPowerLevelsContent,
   IPushRule,
   IPushRules,
+  ISendEventResponse,
   JoinRule,
   MatrixClient,
   MatrixEvent,
@@ -43,6 +44,24 @@ export const getStateEvent = (
 export const getStateEvents = (room: Room, eventType: StateEvent): MatrixEvent[] =>
   room.getLiveTimeline().getState(EventTimeline.FORWARDS)?.getStateEvents(eventType) ?? [];
 
+// Typed state-event write helper.
+//
+// matrix-js-sdk's `sendStateEvent` typed overload rejects the fork's custom
+// `StateEvent` enum values (the `io.lotus.*` / `im.ponies.*` / etc. values in
+// `types/matrix/room.ts`), and casting the event type to `any` at each call site
+// also collapses the `content` argument to `any`. We centralize the single
+// `as any` cast here so every call site keeps its own `content` type checked.
+export function sendStateEvent<T extends object>(
+  mx: MatrixClient,
+  roomId: string,
+  eventType: StateEvent,
+  content: T,
+  stateKey = '',
+): Promise<ISendEventResponse> {
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  return mx.sendStateEvent(roomId, eventType as any, content, stateKey);
+}
+
 export const getAccountData = (
   mx: MatrixClient,
   eventType: AccountDataEvent | string,