refactor: Relocate data module and add README

This commit moves the `model:data` module to a top-level `data` module.
Additionally, a `README.md` file has been added to the project root, providing an overview of the project, architecture, build instructions, current limitations, and suggested improvements.

Key changes:
- Renamed Gradle module `model:data` to `data`.
- Updated `settings.gradle.kts` to reflect the new module path.
- Updated `app/build.gradle.kts` to depend on `projects.data` instead of `projects.model.data`.
- All source files, including `QuizRepositoryImpl`, `QuizMapper`, and `RepositoryModule`, were moved from `model/data/src` to `data/src`.
- Configuration files (`detekt.yml`, `lint-baseline.xml`, `build.gradle.kts`) were moved from `model/data` to `data`.
- Added a new `README.md` file at the project root.

app/build.gradle.kts

@@ -29,7 +29,7 @@ android {
 dependencies {
     implementation(projects.core.designsystem)
     implementation(projects.domain)
-    implementation(projects.model.data)
+    implementation(projects.data)
     implementation(projects.ui.quiz)
 
     implementation(libs.androidx.activity.compose)