[BUG] Dockerfile not being generated during `agentcore configure`

**Describe the bug**
Trying to follow the basic example to deploy a simple MCP as agent and no Dockerfile is being generated. During code build I can see the error in log: Dockerfile no such file or directry

**To Reproduce**
1. Following the instructions in https://docs.aws.amazon.com/bedrock-agentcore/latest/devguide/runtime-mcp.html
2. command `agentcore deploy --local`

**Expected behavior**
A dockerfile created under folder /.bedrock_agentcore/agent_name

**Error Output**
```
Dockerfile: No such file or directory.
```

**Environment:**
- Mac OS
- Python version: 3.10.17
- Package version: 0.2.5
- Installation method: uv pip

**Additional context**
Add any other context about the problem here.

Start with the basic MCP example from the linked AWS documentation and run `agentcore configure`, followed by `agentcore deploy --local`. Check `/.bedrock_agentcore/agent_name` and the build log; done means a Dockerfile is generated there and the local deployment no longer reports that it is missing.

Written by the indexing model from the issue text.