feat(desktop): persistent needs-input indicator + icon button consolidation

Replace the background-clarify toast (expired on alt-tab, easy to miss) with a
persistent, glowing amber "needs input" dot on the session's sidebar row,
driven off a new ClientSessionState.needsInput flag mirrored into a
$attentionSessionIds store. The flag is set on clarify.request and cleared the
moment the turn resumes (tool.complete) or ends.

Also: redesign the clarify tool UI (borderless choices, pseudo-radio dots,
right-aligned checkmark, arc border, tighter padding), make Button the single
source of icon-button styling (4px radius, new icon-titlebar variant, titlebar
buttons rendered polymorphically via asChild, Codicons throughout), put the
file-tree refresh action first, and .trim() pasted composer text.

apps/desktop/src/styles.css

@@ -467,6 +467,37 @@
   --arc-c1: var(--dt-foreground);
 }
 
+/* Quest-style "needs you" pulse for a clarify-blocked session's dot —
+   a soft amber glow that breathes so the row draws the eye without a toast. */
+@keyframes quest-glow {
+  0%,
+  100% {
+    transform: scale(1);
+    box-shadow:
+      0 0 0.1875rem color-mix(in srgb, var(--color-amber-500, #f59e0b) 70%, transparent),
+      0 0 0.5rem color-mix(in srgb, var(--color-amber-500, #f59e0b) 45%, transparent);
+  }
+  50% {
+    transform: scale(1.18);
+    box-shadow:
+      0 0 0.3125rem color-mix(in srgb, var(--color-amber-500, #f59e0b) 90%, transparent),
+      0 0 0.875rem color-mix(in srgb, var(--color-amber-500, #f59e0b) 65%, transparent);
+  }
+}
+
+.quest-glow {
+  animation: quest-glow 1.8s ease-in-out infinite;
+}
+
+@media (prefers-reduced-motion: reduce) {
+  .quest-glow {
+    animation: none;
+    box-shadow:
+      0 0 0.25rem color-mix(in srgb, var(--color-amber-500, #f59e0b) 80%, transparent),
+      0 0 0.625rem color-mix(in srgb, var(--color-amber-500, #f59e0b) 55%, transparent);
+  }
+}
+
 .arc-border::before {
   content: '';
   position: absolute;