feat: personal room name overrides (MSC4431-style)

Users can right-click any room and 'Rename for me...' to set a local
display name visible only to them. Stored in account data under
io.lotus.room_names. Shows a pencil indicator on renamed rooms.
useLocalRoomName() hook overrides useRoomName() when a local name exists.

Also includes:
- Rich room topic rendering via RoomTopicContent object (formatted_body
  support in RoomTopicViewer with HTML sanitization via sanitizeCustomHtml)
- Edit history viewer: clicking '(edited)' on a message opens a modal
  showing all prior versions with timestamps (EditHistoryModal.tsx)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/features/common-settings/general/RoomProfile.tsx

@@ -303,7 +303,7 @@ export function RoomProfile({ permissions }: RoomProfileProps) {
             canEditTopic={canEditTopic}
             avatar={avatar}
             name={name ?? ''}
-            topic={topic ?? ''}
+            topic={topic?.topic ?? ''}
             onClose={handleCloseEdit}
           />
         ) : (
@@ -315,7 +315,7 @@ export function RoomProfile({ permissions }: RoomProfileProps) {
                 </Text>
                 {topic && (
                   <Text className={classNames(BreakWord, LineClamp3)} size="T200">
-                    <Linkify options={LINKIFY_OPTS}>{topic}</Linkify>
+                    <Linkify options={LINKIFY_OPTS}>{topic.topic}</Linkify>
                   </Text>
                 )}
               </Box>