test: validate localization placeholders

[pullfrog]

Summary

• Add a localization test that compares the placeholder sets in every non-English catalog with en-US for every key.
• The test reads the embedded catalogs and reports the language and key on mismatch.

Translation fixes

• None. The new test found no placeholder mismatches in pt-BR or es-ES.

Tests

• dotnet test tests/ConsoleMode.Tests/ConsoleMode.Tests.csproj
• Passed: 134; Failed: 0; Skipped: 0.
• Existing CA1416 warnings were reported for Windows Registry APIs in ProtocolService.cs.
• The Windows app build is left to CI, as required by the repository guidance.

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