fix: GIFs, topic display, formatting toolbar, Copy Link in Invite, support URL

- RoomInput: GIF domain check uses endsWith('.giphy.com') — handles all
  Giphy CDN shards; all silent failure paths now show user-facing error
- RoomProfile: topic plain-text field is now HTML-stripped (no markdown
  syntax visible in header); formatting toolbar (B/I/S/code) above the
  textarea wraps selected text with correct markdown syntax
- InviteUserPrompt: Copy Link button added to dialog header with
  'Copied!' confirmation; removed Copy Link from both three-dot menus
- RoomViewHeader/RoomNavItem: unused copy-link imports removed
- nginx (live): support_page URL updated from lotusguild.org →
  matrix.lotusguild.org

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

src/app/components/invite-user-prompt/InviteUserPrompt.tsx

@@ -34,7 +34,13 @@ import { isKeyHotkey } from 'is-hotkey';
 import FocusTrap from 'focus-trap-react';
 import { stopPropagation } from '../../utils/keyboard';
 import { useDirectUsers } from '../../hooks/useDirectUsers';
-import { getMxIdLocalPart, getMxIdServer, isUserId } from '../../utils/matrix';
+import {
+  getCanonicalAliasOrRoomId,
+  getMxIdLocalPart,
+  getMxIdServer,
+  isRoomAlias,
+  isUserId,
+} from '../../utils/matrix';
 import { Membership } from '../../../types/matrix/room';
 import { useAsyncSearch, UseAsyncSearchOptions } from '../../hooks/useAsyncSearch';
 import { highlightText, makeHighlightRegex } from '../../plugins/react-custom-html-parser';
@@ -42,6 +48,9 @@ import { AsyncStatus, useAsyncCallback } from '../../hooks/useAsyncCallback';
 import { useMatrixClient } from '../../hooks/useMatrixClient';
 import { BreakWord } from '../../styles/Text.css';
 import { useAlive } from '../../hooks/useAlive';
+import { copyToClipboard } from '../../utils/dom';
+import { getMatrixToRoom } from '../../plugins/matrix-to';
+import { getViaServers } from '../../plugins/via-servers';
 
 const SEARCH_OPTIONS: UseAsyncSearchOptions = {
   limit: 1000,
@@ -58,6 +67,15 @@ type InviteUserProps = {
 export function InviteUserPrompt({ room, requestClose }: InviteUserProps) {
   const mx = useMatrixClient();
   const alive = useAlive();
+  const [linkCopied, setLinkCopied] = useState(false);
+
+  const handleCopyLink = () => {
+    const roomIdOrAlias = getCanonicalAliasOrRoomId(mx, room.roomId);
+    const viaServers = isRoomAlias(roomIdOrAlias) ? undefined : getViaServers(room);
+    copyToClipboard(getMatrixToRoom(roomIdOrAlias, viaServers));
+    setLinkCopied(true);
+    setTimeout(() => setLinkCopied(false), 2000);
+  };
 
   const inputRef = useRef<HTMLInputElement>(null);
   const directUsers = useDirectUsers();
@@ -172,7 +190,18 @@ export function InviteUserPrompt({ room, requestClose }: InviteUserProps) {
                     Invite
                   </Text>
                 </Box>
-                <Box shrink="No">
+                <Box shrink="No" gap="100" alignItems="Center">
+                  <Button
+                    size="300"
+                    variant={linkCopied ? 'Success' : 'Secondary'}
+                    fill="Soft"
+                    radii="300"
+                    before={<Icon size="100" src={linkCopied ? Icons.Check : Icons.Link} />}
+                    onClick={handleCopyLink}
+                    aria-label="Copy room link"
+                  >
+                    <Text size="B300">{linkCopied ? 'Copied!' : 'Copy Link'}</Text>
+                  </Button>
                   <IconButton size="300" radii="300" onClick={requestClose} aria-label="Close">
                     <Icon src={Icons.Cross} />
                   </IconButton>