feat(hud): breathing buddy face states (Wave 2-A)

[JeremyDev87]

Buddy face reacts to HUD phase: idle ◕‿◕, thinking ◔‿◔, active ◕◡◕, error ◕︵◕, victory ◕ᴗ◕. Part of #1464.

[JeremyDev87]

Implemented and merged via #1485 (Wave 0-3 integrator) and #1487 (Wave 3b follow-up). Module lives in packages/claude-code-plugin/hooks/lib/. Closing as complete.