Translation Manager: explicit Processing options discriminator

Translation Manager: bumped Jumoo.Processing 17.4.0 → 17.4.2 (NuGet, plus the @jumoo/processing npm floor to ^17.4.2)
Translation Manager: TranslationProcessingOptions now carries [ProcessingOptionsDiscriminator] and is registered via AddProcessingOptionsType<T>() - serialization no longer depends on Processing's type scan, which missed it when uSync.Complete loaded a different Processing.Core version
Translation Manager: discriminator kept as TranslationProcessingOptions so the backoffice $type and persisted pipelines still resolve; added a test that pins it
Opened PR #79 on v17/main