[develop] Fix: Duplicate blocks and mislabeled snippets

[qiutongMS]

Summary

• remove duplicate download blocks and the duplicated summary sentence from the commanding article
• relabel the C++/WinRT feed provider snippet as cpp
• fix the passkey reauthentication sample to use Uint8Array

Validation

• git diff --check -- 'hub/apps/develop/ui/controls/commanding.md' 'hub/apps/develop/feeds/implement-feed-provider-win32.md' 'hub/apps/develop/security/use-cases.md'
• verified sample ZIP links return HTTP 200

[qiutongMS]

Whole-page review found two blocking documentation issues in modified files.

1. hub/apps/develop/security/use-cases.md (passkey enrollment sample): the JavaScript snippet still has id: passkeys.contoso" instead of a quoted string such as id: "passkeys.contoso". As written, the snippet is invalid JavaScript and will mislead readers.

2. hub/apps/develop/testing/index.md (UserControl1 sample): the snippet declares namespace WinUICLassLibrary1, but the surrounding steps and later test code use WinUIClassLibrary1. That namespace mismatch breaks the sample as written.

[qiutongMS]

Summary:
The passkey and commanding edits look good, but the feed-provider article still has a must-fix labeling inconsistency. In a C++/WinRT page, the updated OnFeedProviderEnabled snippet still says // FeedProvider.cs, and several later snippets are still fenced as csharp, so the page remains internally contradictory.

Must-fix issues:

1. hub/apps/develop/feeds/implement-feed-provider-win32.md — In the feed provider implementation sections, the article still mixes C++ code with C# labels (// FeedProvider.cs) and csharp fences (for example OnFeedProviderDisabled / OnFeedEnabled / OnFeedDisabled / OnCustomQueryParametersRequested). Please make the language/file labeling consistent across the page before merge.

[qiutongMS]

Summary: I reviewed the diff and the full modified pages. The changes are technically correct, the updated sample references remain reachable, and the pages read coherently after the edits.

No must-fix issues found.