fix: update DS to v0.1.31, simplify env selector styles

DS v0.1.31 changes .env wrapper to neutral button style matching
other TopBar controls. Simplified selector CSS to inherit all
font/color properties from the wrapper.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/components/EnvironmentSelector.module.css

@@ -2,18 +2,15 @@
   appearance: none;
   background: transparent;
   border: none;
-  padding: 0;
-  margin: -3px -10px;
-  font-family: var(--font-mono);
-  font-size: 10px;
-  font-weight: 600;
+  padding: 0 14px 0 0;
+  margin: 0;
+  font: inherit;
   color: inherit;
-  text-transform: uppercase;
-  letter-spacing: 0.5px;
+  text-transform: inherit;
+  letter-spacing: inherit;
   cursor: pointer;
   outline: none;
   line-height: 1;
-  padding-right: 14px;
   background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='8' height='5' viewBox='0 0 8 5'%3E%3Cpath d='M1 1l3 3 3-3' stroke='currentColor' fill='none' stroke-width='1.5' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
   background-repeat: no-repeat;
   background-position: right 0 center;
@@ -22,6 +19,6 @@
 
 .select:focus-visible {
   outline: 1px solid var(--accent);
-  outline-offset: 4px;
+  outline-offset: 2px;
   border-radius: 2px;
 }