Refine JSDoc examples for consistency and type safety

Follow-up to the examples extraction: pass dependencies as function
parameters instead of using global stub declarations, rename region
names to match method names (e.g., `AppBridge_guestCapabilities_*` →
`AppBridge_getAppCapabilities_*`), and simplify examples using optional
chaining.

Also clarifies `RESOURCE_URI_META_KEY` documentation to indicate it's
for tool definition metadata (from `tools/list`), not tool result
metadata, and removes the redundant `setNotificationHandler` example
in favor of the simpler event setter approach.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/react/useApp.tsx

@@ -29,7 +29,7 @@ export interface UseAppOptions {
    *
    * @param app - The newly created `App` instance
    *
-   * @example Register a notification handler
+   * @example Register an event handler
    * {@includeCode ./useApp.examples.tsx#useApp_registerHandler}
    */
   onAppCreated?: (app: App) => void;
@@ -69,7 +69,7 @@ export interface AppState {
  *   initialization, the `error` field will contain the error (typically connection
  *   timeouts, initialization handshake failures, or transport errors).
  *
- * @example Basic usage
+ * @example Basic usage of useApp hook with common event handlers
  * {@includeCode ./useApp.examples.tsx#useApp_basicUsage}
  *
  * @see {@link App.connect} for the underlying connection method