feat(spec): add WebState + camelCase attribute aliases

WebState extends State with live `document`/`window` for V8-side web
extractors. KnownAttrSelectors gains camelCase aliases (contentDescription,
ariaLabel, testID, etc.) so cross-framework specs autocomplete.

pkg/spec/src/index.ts

@@ -23,6 +23,7 @@ export type {
   TapAction,
   SanderlingRuntime,
   WaitAction,
+  WebState,
   WeightedEntry,
 } from "./types.ts";