refactor(types): typed send helpers replace 16 as any casts (#210)

- sendRoomMessage (composer's fire-and-forget sends: text, location, voice,
  files, GIFs) and sendRoomEvent (polls, poll responses/ends, forwards,
  reactions, edits) in utils/room.ts carry the one cast each needs
  (`keyof TimelineEvents` / `RoomMessageEventContent`, no `any`).
- sendRoomMessage also swallows the rejected promise: a failed send already
  shows on the local echo (Failed to send + Retry, or the consent prompt), so
  it no longer surfaces as an unhandled error in the console.
- getAccountData narrows to `keyof AccountDataEvents`; ForwardMessageDialog's
  guard now narrows `contentToSend` itself (same behaviour).
- `as any` 39 → 23; eslint warnings 46 → 36, ratchet tightened to 36.

Verified in Chromium on a local Synapse: a text message, a quick reaction and
an edit all reach the server with the right content; a consent-blocked send
no longer logs an unhandled MatrixError. 1219 unit tests pass.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/app/utils/room.ts

@@ -1,9 +1,11 @@
 import { IconName, IconSrc } from 'folds';
 
 import {
+  AccountDataEvents,
   EventTimeline,
   EventTimelineSet,
   EventType,
+  IContent,
   IMentions,
   IPowerLevelsContent,
   IPushRule,
@@ -17,8 +19,10 @@ import {
   RelationType,
   Room,
   RoomMember,
+  TimelineEvents,
 } from 'matrix-js-sdk';
 import { CryptoBackend } from 'matrix-js-sdk/lib/common-crypto/CryptoBackend';
+import type { RoomMessageEventContent } from 'matrix-js-sdk/lib/@types/events';
 import { AccountDataEvent } from '../../types/matrix/accountData';
 import {
   IRoomCreateContent,
@@ -62,10 +66,43 @@ export function sendStateEvent<T extends object>(
   return mx.sendStateEvent(roomId, eventType as any, content, stateKey);
 }
 
+// Typed message send for the composer's fire-and-forget sends. The SDK's
+// `sendMessage` wants its `RoomMessageEventContent` union, which the composer's
+// extensible content (MSC3488 location, MSC3245 voice, `m.mentions`, encrypted
+// `file`) doesn't narrow to; the single cast lives here. A failed send already
+// shows on the local echo ("Failed to send" with Retry, or the consent prompt),
+// so the rejection is swallowed rather than surfacing as an unhandled error.
+export function sendRoomMessage(
+  mx: MatrixClient,
+  roomId: string,
+  threadId: string | null,
+  content: IContent,
+): void {
+  mx.sendMessage(roomId, threadId, content as RoomMessageEventContent).catch(() => undefined);
+}
+
+// Typed send for events whose type isn't one of the SDK's typed timeline events
+// (MSC3381 polls, forwarded arbitrary types, the fork's reaction enum) or whose
+// content is extensible. Keeps the one cast out of every call site.
+export function sendRoomEvent(
+  mx: MatrixClient,
+  roomId: string,
+  threadId: string | null,
+  eventType: string,
+  content: IContent,
+): Promise<ISendEventResponse> {
+  return mx.sendEvent(
+    roomId,
+    threadId,
+    eventType as keyof TimelineEvents,
+    content as TimelineEvents[keyof TimelineEvents],
+  );
+}
+
 export const getAccountData = (
   mx: MatrixClient,
   eventType: AccountDataEvent | string,
-): MatrixEvent | undefined => mx.getAccountData(eventType as any);
+): MatrixEvent | undefined => mx.getAccountData(eventType as keyof AccountDataEvents);
 
 export const getMDirects = (mDirectEvent: MatrixEvent): Set<string> => {
   const roomIds = new Set<string>();