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/models/User.kt

@@ -16,6 +16,7 @@ data class User(
     @SerialName("is_active") val isActive: Boolean = true,
     @SerialName("date_joined") val dateJoined: String,
     @SerialName("last_login") val lastLogin: String? = null,
+    @SerialName("auth_provider") val authProvider: String? = null,
     // Profile is included in CurrentUserResponse (/auth/me)
     val profile: UserProfile? = null,
     // Verified is returned directly in LoginResponse, and also in profile for CurrentUserResponse
@@ -206,3 +207,12 @@ data class GoogleSignInResponse(
     val user: User,
     @SerialName("is_new_user") val isNewUser: Boolean
 )
+
+/**
+ * Delete account request matching Go API
+ */
+@Serializable
+data class DeleteAccountRequest(
+    val password: String? = null,
+    val confirmation: String? = null
+)