Replace Spyglass reflection-based discovery with compile-time code generation

[qodo-free-for-open-source-projects]

Description

• The current Spyglass API uses runtime reflection to discover aggregates and states, which is slow and incompatible with AOT compilation
• Need to shift discovery to compile-time using Roslyn incremental source generators
• Must support both traditional aggregates and standalone state types for functional command services
• Generated code should auto-register via module initializers with no DI setup required

Deliverables

• Generator Implementation — Create SpyglassGenerator incremental source generator that discovers Aggregate<T> and State<T> types at compile-time
• Registry System — Implement static SpyglassRegistry to hold discovered types and their metadata (methods, events, load delegates)
• API Refactoring — Update SpyglassApi endpoints to query registry instead of using reflection-based InsidePeek
• Standalone States — Support registration of state-only types without aggregates for functional patterns
• Comprehensive Tests — Add unit tests for generator discovery logic and integration tests for API endpoints

[linear]

EVE-216

[alexeyzimarev]

Fixed in #490