feat: NCS-52 Rules as a microservice (#36)

Implemented module rules as a microservice.
## Summary

   - Adds Quarkus to the `rule` module, making it independently deployable as a standalone microservice on port 8081
   - Exposes all `RuleSet` methods via a REST API at `/api/rules` (candidate moves, legal moves, check/checkmate/stalemate/draw detection, apply
   move)
   - Introduces DTOs and a `DtoMapper` for serializing/deserializing chess types (board, moves, game context) as flat JSON strings
   - Adds `JacksonConfig` for Scala module registration and an `application.yml` for the rule service
   - Includes Dockerfiles for JVM, legacy-jar, native, and native-micro targets
   - Full test coverage: 17 `@QuarkusTest` HTTP-level tests + 29 `DtoMapper` unit tests (100% condition coverage)

   ## Test plan

   - [ ] `./compile` — all modules build successfully
   - [ ] `./test` — all tests pass (rule module: 107 tests total)
   - [ ] `./coverage` — 100% condition coverage in `rule` module
   - [ ] Rule service runs standalone: `./gradlew :modules:rule:quarkusDev` starts on port 8081
   - [ ] `GET /api/rules/candidate-moves` returns valid moves for initial position
   - [ ] `GET /api/rules/is-check` returns `false` for initial position

Co-authored-by: LQ63 <lkhermann@web.de>
Co-authored-by: Janis <janis-e@gmx.de>
Reviewed-on: #36
Co-authored-by: Leon Hermann <lq@blackhole.local>
Co-committed-by: Leon Hermann <lq@blackhole.local>

build.gradle.kts

@@ -41,6 +41,8 @@ val coverageExclusions = listOf(
     "**/io/src/main/scala/de/nowchess/io/service/resource/IoResource.scala",
     // JacksonConfig — Quarkus lifecycle hook, no testable logic beyond ObjectMapper registration
     "**/io/src/main/scala/de/nowchess/io/service/config/JacksonConfig.scala",
+    //RuleSetRestAdapter - Quarkus integration of rule into core, only testable with Quarkus tests
+    "**/core/src/main/de/nowchess/chess/adapter/RuleSetRestAdapter.scala"
 )
 
 // Converts a Sonar-style glob to a scoverage regex (matched against full source path).