feat: Enhance QuizScreen UI and introduce core design system module

This commit significantly revamps the `QuizScreen` UI to display question details including image and text, and introduces a new `core:designsystem` module to centralize theme, colors, typography, and drawable resources.

Key changes:

- **UI Layer (`ui:quiz` module):**
    - Updated `QuizScreen.kt`:
        - Implemented a background image for the screen.
        - Added a `Toolbar` composable to display question progress and type.
        - Created `QuestionContent` composable to show the question image (using Coil for image loading) and text.
        - Added a placeholder `Choices` composable (currently an empty `LazyVerticalGrid`).
        - Applied `fillMaxSize()` to the main `QuizScreen` modifier.
        - Included a `@Preview` for `QuizScreen` with sample data.
    - Modified `QuizScreenViewModel.kt` to update `QuizUiState` with the first `Question` from the fetched quiz.
    - Added a `quiz` string resource in `strings.xml`.
    - Added dependencies for Coil (compose and okhttp) in `ui/quiz/build.gradle.kts`.
- **Core Design System (`core:designsystem` module):**
    - Created a new Android library module `core:designsystem`.
    - Moved `Color.kt`, `Theme.kt`, and `Type.kt` from `app/src/main/java/dev/adriankuta/kahootquiz/ui/theme` to this new module.
    - Added a new `Grey` color to `Color.kt`.
    - Added `bg_image.webp` and `ic_type.xml` drawable resources.
    - Configured the module with `kahootquiz.android.library.compose` plugin.
- **App Module (`app` module):**
    - Updated `MainActivity.kt` to import `KahootQuizTheme` from the new `core.designsystem` package.
    - Added `implementation(projects.core.designsystem)` dependency in `app/build.gradle.kts`.
- **Domain Layer (`domain` module):**
    - Made several fields in `Question.kt` and `Choice.kt` nullable and provided default null values to accommodate potential missing data from the API.
    - Specifically, `Question.image` is now non-nullable (`String`).
- **Build System:**
    - Added `coilCompose` and `coilNetworkOkhttp` versions to `gradle/libs.versions.toml`.
    - Included `:core:designsystem` in `settings.gradle.kts`.

app/build.gradle.kts

@@ -27,10 +27,10 @@ android {
 }
 
 dependencies {
-    implementation(projects.ui.quiz)
+    implementation(projects.core.designsystem)
     implementation(projects.domain)
-
     implementation(projects.model.data)
+    implementation(projects.ui.quiz)
 
     implementation(libs.androidx.activity.compose)
     implementation(libs.androidx.hilt.navigation.compose)

app/src/main/java/dev/adriankuta/kahootquiz/MainActivity.kt

@@ -5,7 +5,7 @@ import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
 import dagger.hilt.android.AndroidEntryPoint
-import dev.adriankuta.kahootquiz.ui.theme.KahootQuizTheme
+import dev.adriankuta.kahootquiz.core.designsystem.KahootQuizTheme
 
 @AndroidEntryPoint
 class MainActivity : ComponentActivity() {

app/src/main/java/dev/adriankuta/kahootquiz/ui/theme/Color.kt

@@ -1,11 +0,0 @@
-package dev.adriankuta.kahootquiz.ui.theme
-
-import androidx.compose.ui.graphics.Color
-
-val Purple80 = Color(0xFFD0BCFF)
-val PurpleGrey80 = Color(0xFFCCC2DC)
-val Pink80 = Color(0xFFEFB8C8)
-
-val Purple40 = Color(0xFF6650a4)
-val PurpleGrey40 = Color(0xFF625b71)
-val Pink40 = Color(0xFF7D5260)

app/src/main/java/dev/adriankuta/kahootquiz/ui/theme/Theme.kt

@@ -1,58 +0,0 @@
-package dev.adriankuta.kahootquiz.ui.theme
-
-import android.app.Activity
-import android.os.Build
-import androidx.compose.foundation.isSystemInDarkTheme
-import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.darkColorScheme
-import androidx.compose.material3.dynamicDarkColorScheme
-import androidx.compose.material3.dynamicLightColorScheme
-import androidx.compose.material3.lightColorScheme
-import androidx.compose.runtime.Composable
-import androidx.compose.ui.platform.LocalContext
-
-private val DarkColorScheme = darkColorScheme(
-    primary = Purple80,
-    secondary = PurpleGrey80,
-    tertiary = Pink80
-)
-
-private val LightColorScheme = lightColorScheme(
-    primary = Purple40,
-    secondary = PurpleGrey40,
-    tertiary = Pink40
-
-    /* Other default colors to override
-    background = Color(0xFFFFFBFE),
-    surface = Color(0xFFFFFBFE),
-    onPrimary = Color.White,
-    onSecondary = Color.White,
-    onTertiary = Color.White,
-    onBackground = Color(0xFF1C1B1F),
-    onSurface = Color(0xFF1C1B1F),
-    */
-)
-
-@Composable
-fun KahootQuizTheme(
-    darkTheme: Boolean = isSystemInDarkTheme(),
-    // Dynamic color is available on Android 12+
-    dynamicColor: Boolean = true,
-    content: @Composable () -> Unit
-) {
-    val colorScheme = when {
-        dynamicColor && Build.VERSION.SDK_INT >= Build.VERSION_CODES.S -> {
-            val context = LocalContext.current
-            if (darkTheme) dynamicDarkColorScheme(context) else dynamicLightColorScheme(context)
-        }
-
-        darkTheme -> DarkColorScheme
-        else -> LightColorScheme
-    }
-
-    MaterialTheme(
-        colorScheme = colorScheme,
-        typography = Typography,
-        content = content
-    )
-}

app/src/main/java/dev/adriankuta/kahootquiz/ui/theme/Type.kt

@@ -1,34 +0,0 @@
-package dev.adriankuta.kahootquiz.ui.theme
-
-import androidx.compose.material3.Typography
-import androidx.compose.ui.text.TextStyle
-import androidx.compose.ui.text.font.FontFamily
-import androidx.compose.ui.text.font.FontWeight
-import androidx.compose.ui.unit.sp
-
-// Set of Material typography styles to start with
-val Typography = Typography(
-    bodyLarge = TextStyle(
-        fontFamily = FontFamily.Default,
-        fontWeight = FontWeight.Normal,
-        fontSize = 16.sp,
-        lineHeight = 24.sp,
-        letterSpacing = 0.5.sp
-    )
-    /* Other default text styles to override
-    titleLarge = TextStyle(
-        fontFamily = FontFamily.Default,
-        fontWeight = FontWeight.Normal,
-        fontSize = 22.sp,
-        lineHeight = 28.sp,
-        letterSpacing = 0.sp
-    ),
-    labelSmall = TextStyle(
-        fontFamily = FontFamily.Default,
-        fontWeight = FontWeight.Medium,
-        fontSize = 11.sp,
-        lineHeight = 16.sp,
-        letterSpacing = 0.5.sp
-    )
-    */
-)