feat(docs): public api kdocs (#658)

- enable rule for checking undocumented public api 
- add kdoc skill

## How Has This Been Tested?
./gradlew detekt

## Breaking Changes
none

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

## Checklist
- [x] I have read the [MCP
Documentation](https://modelcontextprotocol.io)
- [x] My code follows the repository's style guidelines
- [x] New and existing tests pass locally
- [ ] I have added appropriate error handling
- [x] I have added or updated documentation as needed

---------

Co-authored-by: Konstantin Pavlov <1517853+kpavlov@users.noreply.github.com>

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

@@ -51,7 +51,9 @@ private const val MCP_PROTOCOL_VERSION_HEADER = "mcp-protocol-version"
 private const val MCP_RESUMPTION_TOKEN_HEADER = "Last-Event-ID"
 
 /**
- * Error class for Streamable HTTP transport errors.
+ * Represents an error from the Streamable HTTP transport.
+ *
+ * @property code HTTP status code associated with the error, or `null` if unavailable
  */
 public class StreamableHttpError(public val code: Int? = null, message: String? = null) :
     Exception("Streamable HTTP error: $message")
@@ -66,6 +68,9 @@ private sealed interface ConnectResult {
  * Client transport for Streamable HTTP: this implements the MCP Streamable HTTP transport specification.
  * It will connect to a server using HTTP POST for sending messages and HTTP GET with Server-Sent Events
  * for receiving messages.
+ *
+ * @property sessionId session identifier assigned by the server after initialization, or `null` before connection
+ * @property protocolVersion MCP protocol version negotiated with the server, or `null` before connection
  */
 @Suppress("TooManyFunctions")
 public class StreamableHttpClientTransport(