Add quick commands autocomplete dropdown in chat input

Server-authoritative command list via packet 4050, merged with
client-only commands. Supports keyboard navigation, filtering,
and module-level caching to handle login-time packet timing.

Co-Authored-By: medievalshell <medievalshell@users.noreply.github.com>

src/api/room/widgets/CommandDefinition.ts

@@ -0,0 +1,5 @@
+export interface CommandDefinition
+{
+    key: string;
+    description: string;
+}

src/api/room/widgets/index.ts

@@ -7,6 +7,7 @@ export * from './AvatarInfoUser';
 export * from './AvatarInfoUtilities';
 export * from './BotSkillsEnum';
 export * from './ChatBubbleMessage';
+export * from './CommandDefinition';
 export * from './ChatBubbleUtilities';
 export * from './ChatMessageTypeEnum';
 export * from './DimmerFurnitureWidgetPresetItem';