Fix Android pick_file trait imports

AndroidFs trait must be in scope for show_open_file_dialog / read
method resolution — AndroidFsExt alone isn't enough. Matches the
existing share_file pattern that does use both traits.

Caught on the v0.6.1 Android build; previous cargo check only
validated the desktop target.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/tauri-app/src/lib.rs

@@ -1959,7 +1959,7 @@ async fn pick_file(app: tauri::AppHandle, title: String, filter_name: Option<Str
         // and stage them in the app's private cache so existing import code
         // (which expects a path) can read the file normally.
         let _ = (title,);
-        use tauri_plugin_android_fs::AndroidFsExt;
+        use tauri_plugin_android_fs::{AndroidFsExt, AndroidFs};
         let mime_types: Vec<&str> = match filter_ext.as_deref() {
             Some(exts) if exts.iter().any(|e| e == "zip") => vec!["application/zip", "application/octet-stream"],
             _ => vec!["*/*"],