refactor(library): own IgdbGame record, one owned rule, layer rules

Stored import candidates keep their JSON shape, so READY imports from before still read.

readme.md

@@ -194,6 +194,10 @@ Inside a module: `api` (controllers, DTOs), `service` (business logic), `domain`
   `speedrun_adapter`.
 - No cycles between `modules`, `shared` and `configuration`.
 - `api` never uses `repo`, and `repo` never uses `api`.
+- `domain` never uses `api`, `service`, `repo` or an adapter: the import stores IGDB hits as the own record
+  `IgdbGame`, so a change of the adapter's `IgdbApiService.Game` cannot break stored imports.
+- `service` never uses `api`, except the adapters' response DTOs and a fixed list of 8 services that still build
+  their module's response DTOs. The list only gets shorter.
 - Every class in `repo` ends with `Repository`.
 - `shared` never uses `modules`, and `modules` never use `configuration`.
 - A `*Service` class in a module's `service` package has `@Service`. A `*Controller` class in `api` has
@@ -397,7 +401,8 @@ Runs unit, WebMvc, persistence and integration tests plus the ArchUnit rules. Ne
 ## Roadmap
 
 - Sale alerts for wishlist games.
-- Move `steam_adapter` DTOs out of `api`, then turn on strict module independence in ArchUnit.
+- Move the adapter DTOs out of `api`, then turn on strict module independence in ArchUnit and drop the adapter
+  exception of the "`service` never uses `api`" rule.
 
 ## License