feat(badges): slow pulse mode for rainbow punch hole markers

Adds punch_holes.slow_pulse cfg_json flag. When enabled, replaces the fast
2.5s linear hue-rotate with a 6s ease-in-out breathing animation that dims
(0.55 brightness) to bright (1.30) while shifting 180° of hue and back.
Same 120° phase offsets apply (2s apart). Form shows a Slow Pulse checkbox
below the slot cards whenever at least one slot has rainbow enabled.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/ae_events/types/ae_badge_template_cfg.ts

@@ -75,6 +75,7 @@ export interface BadgeTemplateCfg {
         center_fg?: string;
         center_bg?: string;
         center_rainbow?: boolean;
+        slow_pulse?: boolean;    // when true: slow breathing pulse instead of fast linear cycle
     };
 
     // Allow arbitrary extra keys to preserve forward-compatibility.