Fix inherited interface event metadata

[DavidObando]

Summary

• synthesize derived forwarding accessors when an interface event is satisfied by an inherited user event
• wire those accessors with MethodImpl rows for user and imported interfaces, including multi-level and custom-event inheritance
• preserve ordinary inherited method/property dispatch and existing declared custom-event wiring

Validation

• issue gsc metadata: inherited field-like event does not implement interface event #2742 regression matrix: 3/3 (runtime TypeLoad/dispatch + ILVerify + MethodImpl inspection)
• related event emit tests: 66/66
• Compiler.Tests: 3404/3404
• actual cycle-13 Oahu.Core: Oahu.Core.DownloadSettings TypeLoaded; interface targets=10; crash-corrected ILVerify reports 0 DownloadSettings and 0 [MD] findings (64 unrelated pre-existing StackUnexpected findings remain)

Fixes #2742