feat(cron): blueprint start-from + delivery target picker in job editor (issue #780) (#822)

- New-job dialog gains a Start-from dropdown: pick a catalog blueprint, fill its typed slots (time/enum/weekdays/text), save instantiates it via POST /api/cron/blueprints/instantiate
- Delivery field is now an editable picker fed by GET /api/cron/delivery-targets (origin + local + connected platforms)
- Blueprints and targets fetched on editor open; 422 slot errors surface the backend detail

Co-authored-by: M57 <hy4ri@users.noreply.github.com>

app/src/main/java/com/m57/hermescontrol/data/model/CronBlueprint.kt

@@ -0,0 +1,58 @@
+package com.m57.hermescontrol.data.model
+
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.json.JsonElement
+import kotlinx.serialization.json.JsonPrimitive
+
+@Serializable
+data class CronBlueprintListResponse(
+    val blueprints: List<CronBlueprint> = emptyList(),
+)
+
+@Serializable
+data class CronBlueprint(
+    val key: String,
+    val title: String = "",
+    val description: String = "",
+    val category: String = "",
+    val tags: List<String> = emptyList(),
+    val fields: List<CronBlueprintField> = emptyList(),
+    val schedule: String = "",
+    val scheduleHuman: String = "",
+    val command: String = "",
+    val appUrl: String = "",
+)
+
+@Serializable
+data class CronBlueprintField(
+    val name: String,
+    val type: String = "text",
+    val label: String = "",
+    val default: JsonElement? = null,
+    val options: List<String> = emptyList(),
+    val optional: Boolean = false,
+    val strict: Boolean = true,
+    val help: String = "",
+) {
+    val defaultText: String
+        get() = (default as? JsonPrimitive)?.content.orEmpty()
+}
+
+@Serializable
+data class DeliveryTargetsResponse(
+    val targets: List<DeliveryTarget> = emptyList(),
+)
+
+@Serializable
+data class DeliveryTarget(
+    val id: String,
+    val name: String = "",
+    val home_target_set: Boolean = false,
+    val home_env_var: String? = null,
+)
+
+@Serializable
+data class InstantiateBlueprintRequest(
+    val blueprint: String,
+    val values: Map<String, String>,
+)