feat: add space visibility/description, instance re-auth, and per-channel permissions

- Accept visibility and description fields when creating spaces
- Register creator in connectionManager on space creation for immediate WS broadcasts
- Return per-channel myPermissions and space-level myPermissions from GET /spaces/:id
- Populate permission maps in spaceStore from REST response
- Add reauthenticateInstance flow for tokenless federation placeholders
- Handle expired/missing tokens gracefully in autoConnectAll with visible error state
- Guard syncInstanceList against premature runs before autoConnectAll completes

packages/shared/src/types.ts

@@ -300,6 +300,8 @@ export interface AuthResponse {
 export interface CreateSpaceRequest {
   name: string;
   icon?: string;
+  visibility?: SpaceVisibility;
+  description?: string;
 }
 
 export interface CreateChannelRequest {