Fix: Add missing .await for Veilid API shutdown in Android bridge

[tripledoublev]

Description

This PR fixes a type mismatch error in the Android bridge where get_veilid_api() was being called without .await. The function is async and returns a Future<Option<VeilidAPI>>, but was being used as if it returned an Option<VeilidAPI> directly.

Changes

• Added .await to backend.get_veilid_api() call in android_bridge.rs
• This ensures proper async/await handling when shutting down the Veilid API

Fixes the following compilation error:

error[E0308]: mismatched types
--> src/android_bridge.rs:123:28
|
123 | if let Some(veilid_api) = backend.get_veilid_api() {
| ^^^^^^^^^^^^^^^^^^^^^^^^ expected future, found Option<_>