fix(dialogs): Enter in Poll, Schedule, Report dialogs no longer discards input (#315)

Several dialogs are <Box as="form"> with the header ✕ (folds IconButton,
no type attribute, so a submit button) as the form's first button. On
implicit submission, Enter in a text field "clicked" ✕, closing the dialog
and throwing away what was typed (a poll's question and answers, a
schedule, a report reason).

The header close/cancel IconButtons now have type="button": Create Poll,
Schedule Message, Report User, Report Room, Account Data editor, State
Event editor, device verification setup, and the message delete/report
dialogs.

Verified headless: in Create Poll, typing a question and pressing Enter
used to close the dialog; now it stays open with the question kept.

Fixes #315

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

src/app/features/common-settings/developer-tools/StateEventEditor.tsx

@@ -275,7 +275,7 @@ export function StateEventEditor({ type, stateKey, requestClose }: StateEventEdi
             </Chip>
           </Box>
           <Box shrink="No">
-            <IconButton onClick={requestClose} variant="Surface" aria-label="Close">
+            <IconButton type="button" onClick={requestClose} variant="Surface" aria-label="Close">
               <Icon src={Icons.Cross} />
             </IconButton>
           </Box>