fix: federated leaveSpace 403 and context menu for owner spaces

Use getMyUserIdForOrigin() in leaveSpace() so federated spaces send
the correct remote user ID instead of the home ID. Show context menu
for all spaces with "Invite People" action; "Leave Space" only for
non-owners.

packages/web/src/stores/spaceStore.ts

@@ -239,7 +239,7 @@ export const useSpaceStore = create<SpaceState>((set, get) => ({
     const space = get().spaces.find(s => s.id === spaceId);
     const origin = (space as TaggedSpace)?._instanceOrigin ?? '';
     const targetApi = getApiForOrigin(origin);
-    const userId = useAuthStore.getState().user?.id;
+    const userId = getMyUserIdForOrigin(origin);
     if (!userId) return;
     await targetApi.spaces.removeMember(spaceId, userId);
     set((state) => ({