feat: Anweisungen-Feld für Agents mit EasyMDE-Editor

- AgentRecord: TaskInstruction (string, nullable)
- DB-Migration: task_instruction TEXT Spalte
- AgentEndpoint: Create/Update lesen taskInstruction
- SystemPromptBuilder: '## Anweisungen' Block nach Soul, nur wenn nicht leer
- HTML: Textarea #agentTaskInstruction nach Rückfragen-Checkbox
- agent-page.js: EasyMDE-Editor mit Init, Laden, Speichern, Destroy

Services/DatabaseService.cs

@@ -179,6 +179,7 @@ public class DatabaseService
         TryAddColumn(conn, "agents", "avatar_offset_y", "REAL NOT NULL DEFAULT 0");
         TryAddColumn(conn, "sessions", "finalizer_agent_id", "TEXT");
         TryAddColumn(conn, "agents", "allow_user_choice", "INTEGER NOT NULL DEFAULT 1");
+        TryAddColumn(conn, "agents", "task_instruction", "TEXT");
         TryAddColumn(conn, "chains", "plan_mode", "INTEGER NOT NULL DEFAULT 0");
         TryAddColumn(conn, "sessions", "preparer_agent_id", "TEXT");
         TryAddColumn(conn, "messages", "tag", "TEXT");
@@ -334,8 +335,8 @@ public class DatabaseService
         agent.CreatedAt = now;
         agent.UpdatedAt = now;
         await conn.ExecuteAsync(@"
-            INSERT INTO agents (agent_id, user_id, name, avatar, description, model, tool_choice, custom_commands, auto_commit, use_soul, use_identity, use_user_info, use_memory, use_web_search, web_search_version, allow_user_choice, avatar_scale, avatar_offset_x, avatar_offset_y, is_deleted, created_at, updated_at)
-            VALUES (@AgentId, @UserId, @Name, @Avatar, @Description, @Model, @ToolChoice, @CustomCommands, @AutoCommit, @UseSoul, @UseIdentity, @UseUserInfo, @UseMemory, @UseWebSearch, @WebSearchVersion, @AllowUserChoice, @AvatarScale, @AvatarOffsetX, @AvatarOffsetY, 0, @CreatedAt, @UpdatedAt)
+            INSERT INTO agents (agent_id, user_id, name, avatar, description, model, tool_choice, custom_commands, auto_commit, use_soul, use_identity, use_user_info, use_memory, use_web_search, web_search_version, allow_user_choice, task_instruction, avatar_scale, avatar_offset_x, avatar_offset_y, is_deleted, created_at, updated_at)
+            VALUES (@AgentId, @UserId, @Name, @Avatar, @Description, @Model, @ToolChoice, @CustomCommands, @AutoCommit, @UseSoul, @UseIdentity, @UseUserInfo, @UseMemory, @UseWebSearch, @WebSearchVersion, @AllowUserChoice, @TaskInstruction, @AvatarScale, @AvatarOffsetX, @AvatarOffsetY, 0, @CreatedAt, @UpdatedAt)
         ", agent);
         return agent;
     }
@@ -363,7 +364,7 @@ public class DatabaseService
                 model = @Model, tool_choice = @ToolChoice,
                 custom_commands = @CustomCommands, auto_commit = @AutoCommit,
                 use_soul = @UseSoul, use_identity = @UseIdentity, use_user_info = @UseUserInfo, use_memory = @UseMemory, use_web_search = @UseWebSearch, web_search_version = @WebSearchVersion,
-                allow_user_choice = @AllowUserChoice,
+                allow_user_choice = @AllowUserChoice, task_instruction = @TaskInstruction,
                 avatar_scale = @AvatarScale, avatar_offset_x = @AvatarOffsetX, avatar_offset_y = @AvatarOffsetY, updated_at = @UpdatedAt
             WHERE agent_id = @AgentId AND user_id = @UserId
         ", agent);

Services/SystemPromptBuilder.cs

@@ -39,6 +39,12 @@ public static class SystemPromptBuilder
                 blocks.Add(new PromptBlock { Icon = "fa-heart", Label = "Agent · SOUL.md (UseSoul)", Content = soul });
         }
 
+        // Anweisungen
+        if (!string.IsNullOrWhiteSpace(agent.TaskInstruction))
+        {
+            blocks.Add(new PromptBlock { Icon = "fa-clipboard", Label = "Agent · Anweisungen", Content = $"## Anweisungen\n{agent.TaskInstruction.Trim()}" });
+        }
+
         // User-Info: Persona aus dem Profil des Users der gerade schreibt
         if (agent.UseUserInfo && !string.IsNullOrWhiteSpace(userPersona))
         {