fix: use consistent gray background for ActionSelector in light mode (#1581)

### Problem
The ActionSelector container used hardcoded blue theme colors (`blue-1` background, `blue-11` border) which looked inconsistent with the rest of the app in light mode. Other panels (signal cards, detail panes) use `gray-1`/`gray-6`.

### Fix
Changed container background from `var(--blue-1)` → `var(--gray-1)` and border from `var(--blue-11)` → `var(--gray-6)` to match the rest of the app. Interactive elements (selected state, step tabs) still use blue accent colors for emphasis.

Fixes #1556

Author: reverb256

apps/code/src/renderer/components/action-selector/ActionSelector.tsx

@@ -214,8 +214,8 @@ export function ActionSelector({
       }}
       style={{
         outline: "none",
-        border: "1px solid var(--blue-11)",
-        background: "var(--blue-1)",
+        border: "1px solid var(--gray-6)",
+        background: "var(--gray-1)",
         borderRadius: "var(--radius-3)",
       }}
     >