Refactor package structure: domain -> modules

Move domain packages into a new modules.* hierarchy and rename controller packages to api.* across login, registration, and user modules. Update package declarations and imports (including shared.api DTOs and JwtService -> modules login TokenGenerator), adjust tests and persistence/mapper paths accordingly, and apply minor formatting fixes (missing EOF newlines). This reorganizes the project to better separate API surface and module boundaries.

readme.md

@@ -19,20 +19,20 @@ The project strictly follows a Domain-Driven / Clean Architecture (Ports & Adapt
 
 ### Layer Breakdown
 
-1. **Controller / Web Layer (`controller`)**
+1. **API / Web Layer (`api`)**
     * Contains REST endpoints, DTOs (`Request`/`Response` records), and Global Exception Handlers.
     * Uses `ApiMapper` to map between DTOs and Domain Models.
     * **Rule:** This layer delegates to the Service layer and never accesses persistence directly.
 
-2. **Domain / Core Layer (`model`, `service`, `exception`)**
+2. **Business / Core Layer (`model`, `service`, `exception`)**
     * The heart of the application. Contains pure Java classes (Models) and Business Logic (Services).
     * Throws specific business exceptions (e.g., `InvalidCredentialsException`).
-    * **Rule:** This layer has **no dependencies** on the Controller or Persistence layer. It defines interfaces that the persistence layer must implement.
+    * **Rule:** This layer has **no dependencies** on the API or Persistence layer. It defines interfaces that the persistence layer must implement.
 
 3. **Persistence Layer (`persistence`)**
     * Handles database operations. Contains JPA Entities (`UserEntity`), Spring Data Repositories, and the `EntityMapper`.
     * Implements the interfaces defined in the Domain layer.
-    * **Rule:** Entities never leak into the Controller layer.
+    * **Rule:** Entities never leak into the API layer.
 
 *Note: Future implementations will include ArchUnit tests to automatically enforce these architectural boundaries during the CI pipeline.*