Address review: fix mcp-types README deps and v1 migration examples

- README: mcp-types also depends on typing-extensions, not just pydantic.
- migration.md: revert four 'Before (v1)' code blocks the bulk mcp.types ->
  mcp_types rewrite wrongly touched; v1 code imported from mcp.types.

Author: Kludex

docs/migration.md

@@ -435,7 +435,7 @@ The constructor signature also changed — it now takes `code`, `message`, and o
 
 ```python
 from mcp.shared.exceptions import McpError
-from mcp_types import ErrorData, INVALID_REQUEST
+from mcp.types import ErrorData, INVALID_REQUEST
 
 raise McpError(ErrorData(code=INVALID_REQUEST, message="bad input"))
 ```
@@ -679,7 +679,7 @@ This means you can no longer access `.root` on these types or use `model_validat
 **Before (v1):**
 
 ```python
-from mcp_types import ClientRequest, ServerNotification
+from mcp.types import ClientRequest, ServerNotification
 
 # Using RootModel.model_validate()
 request = ClientRequest.model_validate(data)
@@ -901,7 +901,7 @@ The `uri` field on resource-related types now uses `str` instead of Pydantic's `
 
 ```python
 from pydantic import AnyUrl
-from mcp_types import Resource
+from mcp.types import Resource
 
 # Required wrapping in AnyUrl
 resource = Resource(name="test", uri=AnyUrl("users/me"))  # Would fail validation
@@ -986,7 +986,7 @@ The public `server.request_handlers` and `server.notification_handlers` dictiona
 
 ```python
 # Before (v1) — direct dict access
-from mcp_types import ListToolsRequest
+from mcp.types import ListToolsRequest
 
 if ListToolsRequest in server.request_handlers:
     ...

src/mcp-types/README.md

@@ -3,9 +3,9 @@
 The wire types for the [Model Context Protocol](https://modelcontextprotocol.io).
 
 This package holds the protocol message models, JSON-RPC envelope types, per-version
-surface validators, and the protocol-version registry. It depends only on `pydantic`,
-so it can be installed on its own when you need to (de)serialize MCP traffic without
-pulling in the full `mcp` SDK.
+surface validators, and the protocol-version registry. Its only runtime dependencies are
+`pydantic` and `typing-extensions`, so it can be installed on its own when you need to
+(de)serialize MCP traffic without pulling in the full `mcp` SDK.
 
 ```python
 from mcp_types import Tool, CallToolRequest