feat: add Report Room (MSC4151) and fix URL preview default for encrypted rooms

- Report Room: new ReportRoomModal with reason + category, POST /rooms/{id}/report
- URL preview: encUrlPreview default changed to true; security note added to settings

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

src/app/features/room/RoomViewHeader.tsx

@@ -20,6 +20,7 @@ import {
   PopOut,
   RectCords,
   Badge,
+  Chip,
   Spinner,
   Button,
 } from 'folds';
@@ -67,6 +68,7 @@ import { JumpToTime } from './jump-to-time';
 import { useRoomNavigate } from '../../hooks/useRoomNavigate';
 import { useRoomCreators } from '../../hooks/useRoomCreators';
 import { useRoomPermissions } from '../../hooks/useRoomPermissions';
+import { ReportRoomModal } from './ReportRoomModal';
 import { InviteUserPrompt } from '../../components/invite-user-prompt';
 import { ContainerColor } from '../../styles/ContainerColor.css';
 import { RoomSettingsPage } from '../../state/roomSettings';
@@ -92,6 +94,7 @@ const RoomMenu = forwardRef<HTMLDivElement, RoomMenuProps>(({ room, requestClose
   const { navigateRoom } = useRoomNavigate();
 
   const [invitePrompt, setInvitePrompt] = useState(false);
+  const [reportRoomOpen, setReportRoomOpen] = useState(false);
 
   const handleMarkAsRead = () => {
     markAsRead(mx, room.roomId, hideActivity);
@@ -127,6 +130,15 @@ const RoomMenu = forwardRef<HTMLDivElement, RoomMenuProps>(({ room, requestClose
           }}
         />
       )}
+      {reportRoomOpen && (
+        <ReportRoomModal
+          roomId={room.roomId}
+          onClose={() => {
+            setReportRoomOpen(false);
+            requestClose();
+          }}
+        />
+      )}
       <Box direction="Column" gap="100" style={{ padding: config.space.S100 }}>
         <MenuItem
           onClick={handleMarkAsRead}
@@ -227,6 +239,19 @@ const RoomMenu = forwardRef<HTMLDivElement, RoomMenuProps>(({ room, requestClose
       </Box>
       <Line variant="Surface" size="300" />
       <Box direction="Column" gap="100" style={{ padding: config.space.S100 }}>
+        <MenuItem
+          onClick={() => setReportRoomOpen(true)}
+          variant="Critical"
+          fill="None"
+          size="300"
+          after={<Icon size="100" src={Icons.Warning} />}
+          radii="300"
+          aria-pressed={reportRoomOpen}
+        >
+          <Text style={{ flexGrow: 1 }} as="span" size="T300" truncate>
+            Report Room
+          </Text>
+        </MenuItem>
         <UseStateProvider initial={false}>
           {(promptLeave, setPromptLeave) => (
             <>
@@ -478,9 +503,16 @@ export function RoomViewHeader({ callView }: { callView?: boolean }) {
             </Avatar>
           )}
           <Box direction="Column">
-            <Text size={topic ? 'H5' : 'H3'} truncate>
-              {name}
-            </Text>
+            <Box alignItems="Center" gap="200">
+              <Text size={topic ? 'H5' : 'H3'} truncate>
+                {name}
+              </Text>
+              {room.getType() === 'm.server_notice' && (
+                <Chip size="400" variant="Warning" radii="Pill" outlined>
+                  <Text size="T200">Server Notice</Text>
+                </Chip>
+              )}
+            </Box>
             {topic && (
               <UseStateProvider initial={false}>
                 {(viewTopic, setViewTopic) => (