feat: full clean architecture refactor — domain → application → infrastructure → presentation

- Restructure from Modular MVC to Clean Architecture with 4 strict layers
- Domain: entities (anime/komik/proxy), Repository traits, typed errors
- Application: use case classes with proper error propagation
- Infrastructure: repository impls, parsers, Redis cache, HTTP/scraping, browser
- Presentation: Axum handlers, DTOs, AppState, router, AppError+IntoResponse
- Migrate all parsers (otakudesu, alqanime, komik) to native infra implementations
- Replace once_cell::sync::Lazy/OnceCell with std::sync::LazyLock/OnceLock
- Remove 150+ old files in modules/ and shared/ directories
- Remove once_cell from Cargo.toml dependencies
- Fix test/debug binaries to use new import paths
- Zero new clippy warnings

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/observability/openapi.rs

@@ -0,0 +1,14 @@
+use utoipa::OpenApi;
+
+/// Bridge for the auto-generated OpenAPI documentation.
+/// This allows merging manual schema definitions with the auto-discovered handlers and schemas.
+#[derive(OpenApi)]
+#[openapi(
+    // Discovered routes are merged at runtime in bootstrap/mod.rs
+    info(
+        title = "Scraper API",
+        version = "1.0.0",
+        description = "High-performance scraping and CDN microservice"
+    )
+)]
+pub struct ApiDoc;