Migrate to MCP Stateless Protocol - July Beta SDK

[g2vinay]

Migration Plan to MCP Stateless Protocol SDK (Beta)

MCP SDK with major breaking changes is going to ship a beta end of July.

1. Task 1: MCP Protocol and SDK upgrade #2969
2. Task 2: Stateless HTTP transport and routing #2970
3. Task 3: Capability discovery and list caching #2971
4. Task 4: Elicitation migration #2972
5. Task 5: Sampling deprecation and deterministic routing #2973
6. Task 6: JSON Schema 2020-12 tool contracts #2974
7. Task 7: Authorization and remote-host compliance #2975
8. Task 8: Observability and trace context #2976
9. Task 9: Compatibility test harness #2977