[PM-27135] feat: Add Use Passkey screen

[morganzellers-bw]

🎟️ Tracking

PM-27135

📔 Objective

Fourth PR in a 5-PR stack adding SDK-backed passkey test scenarios to TestHarness. Stacked on #2946.

• Adds the "Use Passkey (SDK)" scenario: lists credentials registered via SDKPasskeyService.registeredCredentials, and asserts against the tapped credential's specific credential ID and relying party ID via SDKPasskeyService.assertPasskey, showing the resulting relying party ID and username.
• Wires the new screen into the scenario picker and root navigation.

📸 Screenshots

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Stack: #2945 → #2946 → #2947 → #2948

[github-actions]

🤖 Bitwarden Claude Code Review

Overall Assessment: APPROVE

Reviewed the new "Use Passkey (SDK)" TestHarness scenario: UsePasskeyProcessor/State/View/Action/Effect, the GetAssertionResult fixture, and the routing wired through RootRoute, RootCoordinator, and ScenarioPickerState. The screen follows the same Coordinator-Processor-Store-View shape as the sibling RegisterPasskey screen, all new Localizable.strings keys referenced by the view are defined, and the fixture lives under a Fixtures/ directory that project-bwth.yml excludes from the shipping framework target. Processor tests cover load success/failure, credential-ID and RP-ID pass-through, and assertion success/failure. Both prior findings on this PR (premature empty state, duplicate showScenarioPicker()) are resolved and no new blocking issues were found.

Code Review Details

No findings at or above the reporting threshold.

PR Metadata Assessment

• ❓ QUESTION: The Screenshots section is still a placeholder comment for a PR that adds a new screen — please attach captures of the loading, empty, success, and failure states before merge.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.52%. Comparing base (2bd6942) to head (42b2e54).

Additional details and impacted files

@@                              Coverage Diff                              @@
##           pm-27134-testharness-register-passkeys-ui    #2947      +/-   ##
=============================================================================
- Coverage                                      79.53%   79.52%   -0.02%     
=============================================================================
  Files                                           1169     1169              
  Lines                                          75095    75095              
=============================================================================
- Hits                                           59730    59720      -10     
- Misses                                         15365    15375      +10     

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[github-actions]

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