fix: use OpenCode-compatible list_runs sort schema [BUG-1906]

[rbavery]

Summary

• replace the public list_runs.sort_by tuple parameter with a fixed-length string array so the generated MCP schema uses items instead of tuple prefixItems
• normalize the array back to Flyte's expected (field, direction) tuple internally, preserving existing runtime behavior and response payloads
• add regression coverage for both the normalization path and the generated list_runs schema shape

Why

OpenCode rejects the current list_runs tool schema at startup with:

Invalid schema for function 'flyte-mcp_list_runs': In context=('properties', 'sort_by', 'anyOf', '0'), array schema missing items.

The current tuple annotation emits a JSON Schema array with prefixItems and no items, which Claude and Codex tolerate but OpenCode rejects.

Validation

list my flyte mcp tasks related to inference 
⚙ flyte-mcp-local-test_list_discovery_projects 
⚙ flyte-mcp-local-test_discover_tasks 
Here are the inference-related tasks in your wherobots-rasterflow project (development domain):
Mosaic/Raster Inference (version pr-240-e899ec)
- root_env.run_inference_workflow — Run inference on an index of zarr stores using a specified model
- root_env.run_mosaics_inference_workflow — Run inference on multiple mosaic zarr stores (supports per-row CRS)

[notion-workspace]

compat with opencode