Add delete account feature to mobile app

- DELETE /api/auth/account/ API call in AuthApi + APILayer
- authProvider field on User model for email vs social auth detection
- DeleteAccountDialog with password (email) or "type DELETE" (social) confirmation
- Red "Delete Account" card on ProfileScreen
- Navigation wired in App.kt (clears data, returns to login)
- 10 i18n strings in strings.xml
- ViewModel unit tests for delete account state

composeApp/src/commonMain/kotlin/com/tt/honeyDue/viewmodel/AuthViewModel.kt

@@ -58,6 +58,9 @@ class AuthViewModel : ViewModel() {
     private val _googleSignInState = MutableStateFlow<ApiResult<GoogleSignInResponse>>(ApiResult.Idle)
     val googleSignInState: StateFlow<ApiResult<GoogleSignInResponse>> = _googleSignInState
 
+    private val _deleteAccountState = MutableStateFlow<ApiResult<Unit>>(ApiResult.Idle)
+    val deleteAccountState: StateFlow<ApiResult<Unit>> = _deleteAccountState
+
     fun login(username: String, password: String) {
         viewModelScope.launch {
             _loginState.value = ApiResult.Loading
@@ -271,4 +274,20 @@ class AuthViewModel : ViewModel() {
             APILayer.logout()
         }
     }
+
+    fun deleteAccount(password: String?, confirmation: String?) {
+        viewModelScope.launch {
+            _deleteAccountState.value = ApiResult.Loading
+            val result = APILayer.deleteAccount(password = password, confirmation = confirmation)
+            _deleteAccountState.value = when (result) {
+                is ApiResult.Success -> ApiResult.Success(result.data)
+                is ApiResult.Error -> result
+                else -> ApiResult.Error("Unknown error")
+            }
+        }
+    }
+
+    fun resetDeleteAccountState() {
+        _deleteAccountState.value = ApiResult.Idle
+    }
 }