Integrate FastMCP

This commit integrates FastMCP, a high-level MCP server implementation originally written by Jeremiah Lowin,
into the official MCP SDK. It also updates dependencies and adds new dev dependencies.
It moves the existing SDK into a .lowlevel .

tests/server/fastmcp/resources/test_resources.py

@@ -0,0 +1,100 @@
+import pytest
+from pydantic import AnyUrl
+
+from mcp.server.fastmcp.resources import FunctionResource, Resource
+
+
+class TestResourceValidation:
+    """Test base Resource validation."""
+
+    def test_resource_uri_validation(self):
+        """Test URI validation."""
+
+        def dummy_func() -> str:
+            return "data"
+
+        # Valid URI
+        resource = FunctionResource(
+            uri=AnyUrl("http://example.com/data"),
+            name="test",
+            fn=dummy_func,
+        )
+        assert str(resource.uri) == "http://example.com/data"
+
+        # Missing protocol
+        with pytest.raises(ValueError, match="Input should be a valid URL"):
+            FunctionResource(
+                uri=AnyUrl("invalid"),
+                name="test",
+                fn=dummy_func,
+            )
+
+        # Missing host
+        with pytest.raises(ValueError, match="Input should be a valid URL"):
+            FunctionResource(
+                uri=AnyUrl("http://"),
+                name="test",
+                fn=dummy_func,
+            )
+
+    def test_resource_name_from_uri(self):
+        """Test name is extracted from URI if not provided."""
+
+        def dummy_func() -> str:
+            return "data"
+
+        resource = FunctionResource(
+            uri=AnyUrl("resource://my-resource"),
+            fn=dummy_func,
+        )
+        assert resource.name == "resource://my-resource"
+
+    def test_resource_name_validation(self):
+        """Test name validation."""
+
+        def dummy_func() -> str:
+            return "data"
+
+        # Must provide either name or URI
+        with pytest.raises(ValueError, match="Either name or uri must be provided"):
+            FunctionResource(
+                fn=dummy_func,
+            )
+
+        # Explicit name takes precedence over URI
+        resource = FunctionResource(
+            uri=AnyUrl("resource://uri-name"),
+            name="explicit-name",
+            fn=dummy_func,
+        )
+        assert resource.name == "explicit-name"
+
+    def test_resource_mime_type(self):
+        """Test mime type handling."""
+
+        def dummy_func() -> str:
+            return "data"
+
+        # Default mime type
+        resource = FunctionResource(
+            uri=AnyUrl("resource://test"),
+            fn=dummy_func,
+        )
+        assert resource.mime_type == "text/plain"
+
+        # Custom mime type
+        resource = FunctionResource(
+            uri=AnyUrl("resource://test"),
+            fn=dummy_func,
+            mime_type="application/json",
+        )
+        assert resource.mime_type == "application/json"
+
+    async def test_resource_read_abstract(self):
+        """Test that Resource.read() is abstract."""
+
+        class ConcreteResource(Resource):
+            pass
+
+        with pytest.raises(TypeError, match="abstract method"):
+            ConcreteResource(uri=AnyUrl("test://test"), name="test")  # type: ignore