feat: Implement setup screen and login logic

- Add SetupScreen with UI for server URL, username, and password input.
- Make SetupScreen the initial screen in the navigation graph.
- Implement secure credential storage using EncryptedSharedPreferences.
- Create CredentialsRepository and AuthRepository to manage credentials and auth tokens.
- Add LoginUseCase to handle the business logic for logging in.
- Implement a temporary Retrofit client in ItemRepository to handle login against a user-provided URL.
- Integrate login logic into SetupViewModel.
- Update all relevant project documentation and DI modules.

buildSrc/src/main/java/Dependencies.kt

@@ -94,6 +94,9 @@ object Libs {
     const val composeUiTestJunit4 = "androidx.compose.ui:ui-test-junit4"
     const val composeUiTooling = "androidx.compose.ui:ui-tooling"
     const val composeUiTestManifest = "androidx.compose.ui:ui-test-manifest"
+
+    // Security
+    const val securityCrypto = "androidx.security:security-crypto:${Versions.securityCrypto}"
 }
 
 // [END_FILE_Dependencies.kt]