fix(ui): R10 S4 review r3 — preserve glass-card edge on pills, ease transform

Two low-severity follow-ups from the third /code-review round:
- .pill's resting border-color is now scoped `.pill:not(.glass-card)`, so a
  glass-card-resting pill (PlexSidebar scope/facet, PlexPlaylistView layout)
  keeps glass-card's own border incl. its lighter top-edge specular highlight,
  instead of having it flattened to a uniform var(--border).
- add `transform` to the recipe transition so the `active:translate-y-px` press
  nudge on the Sidebar tag/date pills eases again (it lost the utility transition).

Verified plain pills keep their resting border (Feed + YOUR TAGS) and active
pills still paint solid accent.

frontend/src/index.css

@@ -434,12 +434,19 @@ body {
   .pill,
   .is-current {
     color: var(--muted);
-    border-color: var(--border); /* inert unless the site also adds a border-width utility */
     transition:
       color 0.15s ease,
       background-color 0.15s ease,
       border-color 0.15s ease,
-      box-shadow 0.15s ease; /* so an on-state shadow (Tabs/SettingsPanel) fades in, not pops */
+      box-shadow 0.15s ease,
+      transform 0.15s ease; /* box-shadow: an on-state shadow (Tabs) fades; transform: an active:translate press eases */
+  }
+  /* Resting border colour for the plain pills. NOT applied to a glass-card-resting pill (`.pill.glass-card`),
+     whose own border — including its lighter top-edge specular highlight — must survive. Inert unless the
+     site also adds a border-width utility. */
+  .pill:not(.glass-card),
+  .is-current {
+    border-color: var(--border);
   }
   .pill:hover,
   .is-current:hover {