feat(camera): add CameraDiagnostics static tunable owner
Six knobs for the upcoming retail chase camera: UseRetailChaseCamera
master toggle (env ACDREAM_RETAIL_CHASE), AlignToSlope (env
ACDREAM_CAMERA_ALIGN_SLOPE, default on), TranslationStiffness +
RotationStiffness (both 0.45 retail default), MouseLowPassWindowSec
(0.25), CameraAdjustmentSpeed (40.0). DebugPanel mirror lands later;
this commit just stands up the static surface + defaults + tests.
Per spec docs/superpowers/specs/2026-05-18-retail-chase-camera-design.md.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
5945f1d915