VS screen rework, party selector with fight previews, heal effects on the playout

VS screen rework. The pre-fight VS popup used to crowd hero and enemy cards horizontally; now both sides render as vertical bars with paging chevrons, enemy spells right-aligned, and the layout reads cleanly on both mobile and web. Same content, less cramped.

Party selector picked up real fight previews. Each fight is now grouped into its own column with enemy circles and a reward preview, so when you're picking a party you can see exactly what you're walking into and what drops if you win.

On the playout, healing finally has visual punch. A heal pulse plays on the affected cell, with a floating stat bar surfacing above it — so a heal reads as a beat rather than a number quietly changing. The backend Heal-sigil resolution moved into onCast at the same time, so heal outcomes now show up in the CAST_SPELL event instead of being missed by the playback path.

Two more fixes worth surfacing: KO'd heroes still in their decay window now revive when the fight is won (previously they could end up dead-after-victory in a confusing way), and the fight plan summary renders queued actions as compact purple info chips, so the plan reads at a glance instead of as a wall of text. Small popups got a round of celebratory polish — better copy, more visual punch on rewards.