feat: implement next-task MCP command

- Create direct function wrapper in next-task.js with error handling and caching

- Add MCP tool integration for finding the next task to work on

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

- Update changeset to document the new command

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

@@ -0,0 +1,56 @@
+/**
+ * tools/next-task.js
+ * Tool to find the next task to work on
+ */
+
+import { z } from "zod";
+import {
+  handleApiResult,
+  createErrorResponse
+} from "./utils.js";
+import { nextTaskDirect } from "../core/task-master-core.js";
+
+/**
+ * Register the next-task tool with the MCP server
+ * @param {Object} server - FastMCP server instance
+ */
+export function registerNextTaskTool(server) {
+  server.addTool({
+    name: "next_task",
+    description: "Find the next task to work on based on dependencies and status",
+    parameters: z.object({
+      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 (args, { log }) => {
+      try {
+        log.info(`Finding next task with args: ${JSON.stringify(args)}`);
+        
+        // Call the direct function wrapper
+        const result = await nextTaskDirect(args, log);
+        
+        // Log result
+        if (result.success) {
+          if (result.data.nextTask) {
+            log.info(`Successfully found next task ID: ${result.data.nextTask.id}${result.fromCache ? ' (from cache)' : ''}`);
+          } else {
+            log.info(`No eligible next task found${result.fromCache ? ' (from cache)' : ''}`);
+          }
+        } else {
+          log.error(`Failed to find next task: ${result.error.message}`);
+        }
+        
+        // Use handleApiResult to format the response
+        return handleApiResult(result, log, 'Error finding next task');
+      } catch (error) {
+        log.error(`Error in next-task tool: ${error.message}`);
+        return createErrorResponse(`Failed to find next task: ${error.message}`);
+      }
+    },
+  });
+}