feat: add generation source handling for task creation and updates

backend/src/main/kotlin/com/condado/newsletter/dto/EntityTaskDtos.kt

@@ -1,6 +1,7 @@
 package com.condado.newsletter.dto
 
 import com.condado.newsletter.model.EntityTask
+import com.condado.newsletter.model.TaskGenerationSource
 import jakarta.validation.constraints.NotBlank
 import jakarta.validation.constraints.NotNull
 import java.time.LocalDateTime
@@ -11,7 +12,8 @@ data class EntityTaskCreateDto(
     @field:NotBlank val name: String,
     val prompt: String,
     @field:NotBlank val scheduleCron: String,
-    @field:NotBlank val emailLookback: String
+    @field:NotBlank val emailLookback: String,
+    val generationSource: TaskGenerationSource = TaskGenerationSource.LLAMA
 )
 
 data class EntityTaskUpdateDto(
@@ -19,7 +21,8 @@ data class EntityTaskUpdateDto(
     @field:NotBlank val name: String,
     @field:NotBlank val prompt: String,
     @field:NotBlank val scheduleCron: String,
-    @field:NotBlank val emailLookback: String
+    @field:NotBlank val emailLookback: String,
+    val generationSource: TaskGenerationSource? = null
 )
 
 data class EntityTaskResponseDto(
@@ -29,6 +32,7 @@ data class EntityTaskResponseDto(
     val prompt: String,
     val scheduleCron: String,
     val emailLookback: String,
+    val generationSource: TaskGenerationSource,
     val active: Boolean,
     val createdAt: LocalDateTime?
 ) {
@@ -41,6 +45,7 @@ data class EntityTaskResponseDto(
                 prompt = task.prompt,
                 scheduleCron = task.scheduleCron,
                 emailLookback = task.emailLookback,
+                generationSource = task.generationSource,
                 active = task.active,
                 createdAt = task.createdAt
             )