fix: type-safe proto enums, MCP protocol compliance, TUI teardown
- Replace hardcoded i32 enum matches with ProtoEnum::try_from() in
8 command files (cluster, config, data, model, risk, service, train, tune)
- Replace hardcoded i32 literals with enum variants (EmergencyStopType,
ExportFormat, TrainingMode)
- Add JSON-RPC 2.0 PARSE_ERROR (-32700) for malformed JSON input
- Validate jsonrpc:"2.0" version on incoming MCP requests
- Change unreachable execute_tool catch-all from Ok to Err
- Fix TUI teardown to not mask original event_loop error
- Rename config_cmd module to config (commands::config)
- 77 tests pass, 0 clippy warnings
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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