[fix](trx-frontend-http): remove animation from spectrum center-shift arrows

The global button transition and the :active scale(0.97) transform were
interfering with the translateY(-50%) centering, making the buttons jump
on press. Added transition:none and reduced :active to translateY(-50%)
only (no scale).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

src/trx-client/trx-frontend/trx-frontend-http/assets/web/style.css

@@ -2306,6 +2306,7 @@ button:focus-visible, input:focus-visible, select:focus-visible {
   box-shadow: 0 8px 18px rgba(0,0,0,0.18);
   backdrop-filter: blur(10px);
   -webkit-backdrop-filter: blur(10px);
+  transition: none;
 }
 .spectrum-edge-shift::before {
   content: "";
@@ -2326,7 +2327,7 @@ button:focus-visible, input:focus-visible, select:focus-visible {
   border-color: var(--accent-yellow);
 }
 .spectrum-edge-shift:active {
-  transform: translateY(-50%) scale(0.97);
+  transform: translateY(-50%);
 }
 .spectrum-edge-shift-left {
   left: -2.05rem;