feat: domain mocks, TestContextBuilder, use case tests, factory pattern

- Add test-helpers feature to domain crate with in-memory mocks and panic stubs for all ports
- Add TestContextBuilder to application crate for zero-database test setup
- Add unit tests for log_review, register, login, add_to_watchlist, delete_review use cases
- Extract DatabaseAdapters factory and build_* helpers into presentation/src/factory.rs
- Refactor wire_dependencies() in main.rs to use factory module

crates/presentation/src/lib.rs

@@ -1,6 +1,7 @@
 pub mod csrf;
 pub mod errors;
 pub mod extractors;
+pub mod factory;
 pub mod forms;
 pub mod handlers;
 pub mod openapi;