[Unit 2] FastMCP renaming

Hi! In **Unit 2**, all MCP server development snippets use `FastMCP`.

In version **2.0** of the `modelcontextprotocol` Python SDK, `FastMCP` was renamed to `MCPServer`. The examples should be updated to use the new class and import path.

**Before — v1:**

```python
from mcp.server.fastmcp import FastMCP

mcp = FastMCP("Demo")
```

**After — v2:**

```python
from mcp.server.mcpserver import MCPServer, Context

mcp = MCPServer("Demo")
```

Reference: [Migration guide from v1 to v2](https://py.sdk.modelcontextprotocol.io/migration/?h=FastMCP#mcpserver-formerly-fastmcp)

Locate the Unit 2 code snippets that import and instantiate FastMCP, then review the linked v1-to-v2 migration guide for the required names and import path. Update the examples to use MCPServer and Context as shown, and confirm that Unit 2 no longer contains the outdated FastMCP usage.

Written by the indexing model from the issue text.