ci(safeway): gate MCP evals in Modal

[walkerhughes]

Summary

• add four deterministic Harbor tasks for nearest-store selection, milk pricing, product refresh, and basket totals
• grade both exact task outcomes and required Safeway MCP usage
• reject direct mock-endpoint bypasses, including delegated tool calls
• run unit checks and the Harbor gate in Modal on Safeway changes
• bump the plugin version to 0.1.1 so Claude Code refreshes its cache

Verification

• make check
• make coverage (89%)
• 28 local process-check cases and 16 local outcome-check cases
• Harbor 0.18 Modal job configuration resolution
• official plugin and skill validators

Stack

Depends on #69, which depends on #68.