test: verify spring URL with Spring AI WebFlux and WebMVC

[soubhagya-behera]

Summary

• Add Spring AI WebMVC and WebFlux end-to-end regression coverage for the spring: URL scheme.
• Verify MCP initialization, tool discovery, tool descriptions, and tool schemas against both server stacks.
• Add the required test-scoped Spring AI MCP server dependencies and document the WebFlux coverage.

Testing

• mvn -B test
• 55 tests passed
• 0 failures
• 0 errors
• 0 skipped