refactor(theme): centralize colors and typography in AppColors and AppTypography

- Replaced hardcoded color values in `LightColorScheme` and `DarkColorScheme` with `AppColors`.
- Updated `AppTypography` references in `AppMaterialTypography`.
- Upgraded Kotlin, Compose Multiplatform, and Ktor to latest versions in `libs.versions.toml`.
- Added `uiToolingPreview` dependency in `meldestelle-portal` build script.
- Refactored config loading to include `RequestInit`.

Signed-off-by: Stefan Mogeritsch <stefan.mo.co@gmail.com>

gradle/libs.versions.toml

@@ -7,7 +7,7 @@
 # === FRONTEND & KMP CORE ===
 # ==============================================================================
 # Kotlin & Tooling
-kotlin = "2.3.0"
+kotlin = "2.3.20"
 ksp = "2.3.4"
 
 # KotlinX (Core Libraries)
@@ -17,14 +17,14 @@ kotlinx-datetime = "0.7.1"
 
 # UI: Compose Multiplatform
 # Aligned with Kotlin 2.3.0
-composeMultiplatform = "1.10.0"
+composeMultiplatform = "1.11.0-alpha04"
 composeHotReload = "1.0.0"
 androidx-lifecycle = "2.9.6"
 uiDesktop = "1.7.0"
 
 # Network: Ktor (Client & Server)
 # Align with Kotlin 2.3.0 – upgrade to 3.4.0 (runtime OpenAPI + lifecycle improvements)
-ktor = "3.4.0"
+ktor = "3.4.1"
 
 # Dependency Injection
 koin = "4.1.1"