Side-by-side layout & style presets

2-column layout

Modules scroll on the left, preview is always visible on the right (no more toggle)
Matches the native HA card editor's side-by-side structure
Dialog height expanded to 92vh when the Style panel opens
Preset system

💾 Save button — prompts for a name, saves current module state
📋 Load preset… dropdown — applying a preset immediately updates the card
× delete button — appears when a preset is selected
Stored in browser localStorage under key cms-presets

What's Changed

• v0.3.11 — 2-column layout, live preview right-side, style presets by @DerTrolli in #9

Full Changelog: v0.3.10...v0.3.11