This PR fixes four bugs:

1. Incorrect format in mcpClient configuration generation.
2. Passes the argsPosition parameter down to the RequestTemplate.
3. Fixes inconsistent URL processing in the handler method of Selector and Rule in the McpServer plugin.
4. Adds a null value check in SelectorHandler of the McpServer plugin.

Make sure that:

• You have read the contribution guidelines.
• You submit test cases (unit or integration tests) that back your changes.
• Your local test passed ./mvnw clean install -Dmaven.javadoc.skip=true.