feat: add structured capability types

Replace generic capability dictionaries with structured types for prompts,
resources, tools, and roots. This improves type safety and makes capability
features like listChanged and subscribe more explicit in the protocol.

mcp_python/__init__.py

@@ -33,10 +33,13 @@ from .types import (
     Notification,
     PingRequest,
     ProgressNotification,
+    PromptsCapability,
     ReadResourceRequest,
     ReadResourceResult,
     Resource,
+    ResourcesCapability,
     ResourceUpdatedNotification,
+    RootsCapability,
     SamplingMessage,
     ServerCapabilities,
     ServerNotification,
@@ -46,6 +49,7 @@ from .types import (
     StopReason,
     SubscribeRequest,
     Tool,
+    ToolsCapability,
     UnsubscribeRequest,
 )
 from .types import (
@@ -82,10 +86,13 @@ __all__ = [
     "Notification",
     "PingRequest",
     "ProgressNotification",
+    "PromptsCapability",
     "ReadResourceRequest",
     "ReadResourceResult",
+    "ResourcesCapability",
     "ResourceUpdatedNotification",
     "Resource",
+    "RootsCapability",
     "SamplingMessage",
     "SamplingRole",
     "ServerCapabilities",
@@ -98,6 +105,7 @@ __all__ = [
     "StopReason",
     "SubscribeRequest",
     "Tool",
+    "ToolsCapability",
     "UnsubscribeRequest",
     "stdio_client",
     "stdio_server",