[codex] Update key invalidation period options

[SirAndrosBot]

What changed

• Removed 10 Minutes from the saved-key invalidation dropdown.
• Kept the existing 3 Days option available in the same dropdown.
• Updated the dropdown index mapping after removing the 10-minute row.
• Preserved compatibility with existing configurations that already contain the 10-minute value by showing them as the nearest remaining visible option, 15 Minutes.

Why

Issue #40 asks for safer saved-key invalidation behavior and discusses scan-attempt limits. The scan-attempt part is not implemented here because KeePassWinHello delegates the biometric prompt to Windows Hello/CNG. The plugin does not receive per-failed-scan events, so adding a setting named as a scan-attempt limit would not actually control fingerprint attempts. Reusing the existing provider retry count would be misleading because that value applies to whole retryable provider/system operations, not individual biometric scans inside the Windows Hello prompt.

This PR implements the low-risk, defensible part: removing the very short 10-minute retention option while preserving existing saved settings without breaking option loading.

Refs #40

Validation

• Worker subagent implemented the change in an isolated branch.
• Reviewer subagent checked the mapping and found no actionable issues.
• git diff --check
• MSBuild.exe src\KeePassWinHello.csproj /t:Rebuild /p:Configuration=Release /p:DefineConstants=MONO /p:FrameworkPathOverride=C:\Windows\Microsoft.NET\Framework\v4.0.30319 /p:ReferencePath=C:\proj\KeePassWinHello\lib

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud