Reorganize & modernize for HA 2026.5

What's new

• Switches now use the modern ha-switch-* variables — they were silently broken on recent HA versions. Includes a soft thumb glow on the on-colour accent.
• Checkboxes themed via the new ha-checkbox-* family (new in HA 2026.5).
• Progress bars themed via the new ha-progress-bar-* family (new in HA 2026.5).
• Global surface tokens: ha-color-surface-low / ha-color-surface-lower.
• Global box-shadow tokens: ha-box-shadow-s / m / l.
• Tighter spacing: ha-space-3/ha-space-4 and ha-view-sections-row-gap/column-gap for snappier card layout.

Maintenance

• Removed deprecated paper-style switch-checked-color / switch-unchecked-* (officially removed in HA 2026.5).
• File reorganized into clear logical sections (Theme Variables, Main Interface, Backgrounds, Cards, Inputs, Switches, Checkboxes, Sliders, Progress Bars, Icons/States, Tables, Code Editor).
• Comment typos fixed; standardized YAML quoting on rgb() / rgba() values.

Compatibility: Requires Home Assistant 2026.5 or later for full styling. On older HA versions the new tokens are simply ignored.