Add press effect, glow, arrow slide, easing, and backdrop blur to nav buttons

- :active scale(0.95) press feel on all nav buttons
- box-shadow glow ring on hover (accent @ 20% opacity)
- cubic-bezier(.2,0,0,1) iOS-style snap easing on all transitions
- backdrop-filter: blur(10px) frosted glass base on all buttons
- Dashboard → arrow wraps in <span class="arr"> and slides 2px right on hover

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

app/public/style.css

@@ -124,14 +124,22 @@ a:hover { text-decoration: underline; }
   padding: 0.35rem 0.85rem;
   border: 1px solid var(--border);
   border-radius: 8px;
-  background: transparent;
-  transition: background .15s, border-color .15s, color .15s;
+  background: color-mix(in srgb, white 5%, transparent);
+  backdrop-filter: blur(10px);
+  -webkit-backdrop-filter: blur(10px);
+  transition: background .18s cubic-bezier(.2,0,0,1),
+              border-color .18s cubic-bezier(.2,0,0,1),
+              color .18s cubic-bezier(.2,0,0,1),
+              box-shadow .18s cubic-bezier(.2,0,0,1),
+              transform .1s cubic-bezier(.2,0,0,1);
 }
 .station-link:hover {
   background: color-mix(in srgb, var(--accent) 18%, transparent);
   border-color: var(--accent);
   color: var(--accent);
+  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 20%, transparent);
 }
+.station-link:active { transform: scale(0.95); box-shadow: none; }
 
 .settings-nav-links {
   display: flex;