Release v15.41.0

Added

• CHR0034 — error when [PII] is applied to a property or record parameter whose type derives from EventSourceId<T>. The event source id is the encryption-key lookup identity, so Chronicle throws PIINotSupportedOnEventSourceId at runtime; the analyzer turns that into a compile-time error.
• CHR0035 — error when a [ReadModel] declares a property or record parameter named _subject, which Chronicle reserves as an internal MongoDB field for compliance-subject tracking.
• CHR0036 — warning when a reducer declares mutable instance state or injects a storage primitive such as IMongoCollection<T>. Reducers must be stateless for deterministic replay; this mirrors CHR0031/CHR0032 for reactors. (#958)
• CHR0037 — warning when the two generations referenced by an EventTypeMigration<TUpgrade, TPrevious> do not share one explicit [EventType] id. Chronicle keys generations by that id, so absent or differing ids mean the migration silently never applies.

Fixed

• ReadModelScenario<T> now backfills the joined value for a root-level [Join] whose join-source event is keyed by a string concept, matching the parity a Guid-keyed join already had.