ui: Refactor data-attrs constants, enum for bool strings (#27002)

* refactor: Data-attribute constants + boolean string enum

* refactor: Use CSS class string constants

* refactor: Address review comments

tools/ui/src/lib/enums/index.ts

@@ -33,6 +33,8 @@ export {
 
 export { SessionRecordType } from './conversation-import.enums';
 
+export { BooleanString } from './boolean-string.enums';
+
 export { ReasoningEffort } from './reasoning-effort.enums';
 
 export {