feat(themes): summer pair JSON SoT + status CSS + recapture previews

Align summer-day/night waybar tokens with JSON roles (hierarchy split
on night; day overlay≠muted), unify bar font 13px + battery 25/10, add
VPN pill and status states (.on/.available/.recording/…). Recapture
executive-slate and neon-glass picker previews from theme-shot.

Verified: V0 contrast+wholeswap; V2 theme-shot four slugs.

themes/summer-day/waybar.jsonc

@@ -57,7 +57,7 @@
 
   "battery": {
     "interval": 60,
-    "states": { "warning": 30, "critical": 15 },
+    "states": { "warning": 25, "critical": 10 },
     "max-length": 10,
     "format": "<span size='13pt'>{icon}</span>  {capacity}%",
     "format-charging": "<span size='13pt'></span> {capacity}%",