WHY:
- HLS (Haskell) and rust-analyzer use Void/unit types for shutdown/exit
- These strict-typed servers reject ANY params field (even empty {})
- PR #851 changed to send params:{} for Delphi/FPC compatibility
- This broke HLS/rust-analyzer with "Cannot parse Void" errors
EXPECTED:
- shutdown/exit methods: omit params field entirely (HLS/rust-analyzer compat)
- Other methods with None: send params:{} (Delphi/FPC compat)
- Other methods with params: include them unchanged (standard behavior)
- Three-way compatibility preserved per JSON-RPC 2.0 spec
Refs: oraios/serena#870
