fix(desktop): Lotus links use the public web app, and open in-app (#248)

Lotus permalinks (#130) were built from window.location.origin. In the
desktop app that's the local tauri-plugin-localhost server (hash-routed), so
"Copy Lotus Link" copied e.g. http://localhost:…/#/home/!room…, which works
for nobody else. And the link recogniser only knew that local base, so a real
https://chat.lotusguild.org/home/… link in a message opened the browser
instead of the room.

- useLotusShareBase: in the desktop app, links for other people use config
  `webAppUrl` (https only, set by cinny-desktop #23) in web path-routing
  form; otherwise the origin, as before. Used by "Copy Lotus Link" on
  messages, the space menu and space tabs.
- The recogniser accepts several bases: the origin, plus `webAppUrl` in the
  desktop app.
- The web app is unchanged.

Verified with a simulated desktop (Tauri bridge + webAppUrl) against a local
Synapse. Copied links are https://chat.lotusguild.org/home/<room>/<event> and
https://chat.lotusguild.org/<space>. A public link in a message renders as
the room pill and clicking it opens the room in-app, with nothing sent to the
system browser. The web app still copies origin links. Unit tests for the
base selection; Playwright 20 passed.

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

src/app/features/room/message/Message.tsx

@@ -83,8 +83,6 @@ import { copyToClipboard } from '../../../utils/dom';
 import { stopPropagation } from '../../../utils/keyboard';
 import { getMatrixToRoomEvent } from '../../../plugins/matrix-to';
 import { getLotusRoomPermalink } from '../../../plugins/lotus-permalink';
-import { getOriginBaseUrl } from '../../../pages/pathUtils';
-import { useClientConfig } from '../../../hooks/useClientConfig';
 import { getViaServers } from '../../../plugins/via-servers';
 import { useMediaAuthentication } from '../../../hooks/useMediaAuthentication';
 import { useRoomPinnedEvents } from '../../../hooks/useRoomPinnedEvents';
@@ -98,6 +96,7 @@ import { useLongPress } from '../../../hooks/useLongPress';
 import { ActionSheet } from '../../../components/action-sheet';
 import { useBookmarks } from '../../../hooks/useBookmarks';
 import { PresenceRingAvatar } from '../../../components/presence';
+import { useLotusShareBase } from '../../../hooks/useLotusLinkBase';
 import { AvatarDecoration } from '../../../components/avatar-decoration/AvatarDecoration';
 
 // Delivery status indicator for own messages
@@ -460,18 +459,11 @@ export const MessageCopyLotusLinkItem = as<
     onClose?: () => void;
   }
 >(({ room, mEvent, onClose, ...props }, ref) => {
-  const { hashRouter } = useClientConfig();
+  const lotusBase = useLotusShareBase();
   const handleCopy = () => {
     const eventId = mEvent.getId();
     if (!eventId) return;
-    copyToClipboard(
-      getLotusRoomPermalink(
-        getOriginBaseUrl(hashRouter),
-        room.roomId,
-        eventId,
-        getViaServers(room),
-      ),
-    );
+    copyToClipboard(getLotusRoomPermalink(lotusBase, room.roomId, eventId, getViaServers(room)));
     onClose?.();
   };