v0.5.31

• Align the frontend shell with the documented Home Assistant visual line: remove decorative dot-field/gradient/glassmorphism effects, use solid surfaces, moderate card elevation, medium-radius controls, and semantic spacing tokens.
• Change responsive client and audit presentations to switch at the content breakpoint of 900px instead of 1600px.
• Refresh deterministic visual baselines and UX contracts for light/dark, reduced motion, responsive geometry, and static-shell behavior.