test: add real FastMCP integration coverage

[barvhaim]

Summary:

• Add a real FastMCP integration test that wraps a server with HoneyMCP.
• Verify both a regular tool call and a static ghost tool call work end to end.
• Remove one unused middleware import after merging current master.

Testing:

• uv run pytest -q tests/test_fastmcp_integration.py
• uv run --with fastmcp==3.4.2 pytest -q tests/test_fastmcp_integration.py
• uv run ruff check src/honeymcp/core/fingerprinter.py src/honeymcp/core/middleware.py tests/test_fastmcp_integration.py