feat: add URL mode elicitation and typed schema definitions per MCP (#660)

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

conformance-test/run-conformance.sh

@@ -9,7 +9,7 @@ set -uo pipefail
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" || exit 1; pwd)"
 PROJECT_ROOT="$(cd "$SCRIPT_DIR/.." || exit 1; pwd)"
 
-CONFORMANCE_VERSION="0.1.15"
+CONFORMANCE_VERSION="0.1.16"
 PORT="${MCP_PORT:-3001}"
 SERVER_URL="http://localhost:${PORT}/mcp"
 RESULTS_DIR="$SCRIPT_DIR/results"