Add URL mode elicitation support and typed `PrimitiveSchemaDefinition`
hierarchy to align with MCP specification 2025-11-25
closes#540
## How Has This Been Tested?
unit/integration/conformance
## Breaking Changes
- `ElicitRequestParams` changed from `data class` to `sealed interface`.
A deprecated factory function preserves source compatibility for
`ElicitRequestParams(message, requestedSchema)`.
- `RequestedSchema.properties` changed from `JsonObject` to `Map<String,
PrimitiveSchemaDefinition>`.
- `ElicitRequest.requestedSchema` is deprecated, use `(params as
ElicitRequestFormParams).requestedSchema`.
## Types of changes
- [ ] Bug fix (non-breaking change which fixes an issue)
- [x] New feature (non-breaking change which adds functionality)
- [x] Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] 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
- [x] I have added appropriate error handling
- [x] I have added or updated documentation as needed
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