[codex] fix focus list array response

[JeelyWu]

Summary

• Support both wrapped {focuses: [...]} and top-level array responses from the focus list endpoint.
• Add a regression test for the array response shape observed against dida365.

Root Cause

focus ls decoded the focus list response only as an object with a focuses field, but the dida365 API can return a top-level JSON array.

Validation

• make test
• make smoke
• Manual end-to-end CLI coverage for focus and the broader command set before this commit.