refactor: rename Server → Space across entire codebase

Renames all domain terminology from "Server" to "Space" throughout the
application — database schema, API routes, shared types, stores, components,
and UI strings. Files renamed: ServerSidebar → SpaceSidebar, CreateServer →
CreateSpace, JoinServer → JoinSpace, ServerSettings → SpaceSettings,
serverStore → spaceStore, routes/servers → routes/spaces.

packages/web/src/utils/voice.ts

@@ -1,5 +1,5 @@
 import { useVoiceStore } from '../stores/voiceStore';
-import { getChannelOrigin, getMyUserIdForOrigin } from '../stores/serverStore';
+import { getChannelOrigin, getMyUserIdForOrigin } from '../stores/spaceStore';
 import { wsSend } from '../hooks/useWebSocket';
 
 /**