fix!: Migrate Ktor extension functions from Routing to Route (#237) (#531)

# Migrate Ktor extension functions from `Routing` to `Route` (#237)

- Replaced `Routing` with `Route` in MCP-related functions for better
composability in nested contexts.
- Updated tests to verify compatibility with nested routes and subpaths.
- Deprecated legacy signatures and removed redundant overloads.

## How Has This Been Tested?
Unit test

## Breaking Changes
`Routing.mcp(...) `extension was replaced with `Route.mcp(...)`

## Types of changes

- [X] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [x] Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] Documentation update

## Checklist
<!-- Go over all the following points, and put an `x` in all the boxes
that apply. -->
- [x] I have read the [MCP
Documentation](https://modelcontextprotocol.io)
- [x] My code follows the repository's style guidelines
- [ ] New and existing tests pass locally
- [ ] I have added appropriate error handling
- [ ] I have added or updated documentation as needed

## Additional context
Based on #314 by @IainHull but that PR is too outdated.

kotlin-sdk-client/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/client/KtorClient.kt

@@ -13,7 +13,7 @@ import kotlin.time.Duration
  * @param urlString Optional URL of the MCP server.
  * @param reconnectionTime Optional duration to wait before attempting to reconnect.
  * @param requestBuilder Optional lambda to configure the HTTP request.
- * @return A [SSEClientTransport] configured for MCP communication.
+ * @return A [SseClientTransport] configured for MCP communication.
  */
 public fun HttpClient.mcpSseTransport(
     urlString: String? = null,