feat: implement add-task MCP command

- Create direct function wrapper in add-task.js with prompt and dependency handling

- Add MCP tool integration for creating new tasks via AI

- Update task-master-core.js to expose addTaskDirect function

- Update changeset to document the new command

mcp-server/src/tools/add-task.js

@@ -0,0 +1,47 @@
+/**
+ * tools/add-task.js
+ * Tool to add a new task using AI
+ */
+
+import { z } from "zod";
+import {
+  handleApiResult,
+  createErrorResponse
+} from "./utils.js";
+import { addTaskDirect } from "../core/task-master-core.js";
+
+/**
+ * Register the add-task tool with the MCP server
+ * @param {Object} server - FastMCP server instance
+ */
+export function registerAddTaskTool(server) {
+  server.addTool({
+    name: "add_task",
+    description: "Add a new task using AI",
+    parameters: z.object({
+      prompt: z.string().describe("Description of the task to add"),
+      dependencies: z.string().optional().describe("Comma-separated list of task IDs this task depends on"),
+      priority: z.string().optional().describe("Task priority (high, medium, low)"),
+      file: z.string().optional().describe("Path to the tasks file"),
+      projectRoot: z.string().optional().describe("Root directory of the project (default: current working directory)")
+    }),
+    execute: async ({ prompt, dependencies, priority, file, projectRoot }, log) => {
+      try {
+        log.info(`MCP add_task called with prompt: "${prompt}"`);
+        
+        const result = await addTaskDirect({
+          prompt,
+          dependencies,
+          priority,
+          file,
+          projectRoot
+        }, log);
+        
+        return handleApiResult(result);
+      } catch (error) {
+        log.error(`Error in add_task MCP tool: ${error.message}`);
+        return createErrorResponse(error.message, "ADD_TASK_ERROR");
+      }
+    }
+  });
+}