[style](trx-frontend-http): fade the scrolled tab strip edge

The page tabs scroll rather than wrap, so the last visible tab was sliced
mid-word ("Se…" for Settings), which reads as a rendering fault instead of
as an invitation to scroll.

Fade the trailing edge with a mask.  A colour-matched cover gradient is
the usual trick, but the card is transparent, so a cover would have to
track the page background across both themes and all nine styles; a mask
is colour-agnostic.  Only the trailing edge is faded, leaving the first
tab crisp while the strip sits at rest.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GdyUjuXejCEfiub675z6cz
Signed-off-by: Stan Grams <sjg@haxx.space>

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

@@ -1549,6 +1549,15 @@ small { color: var(--text-muted); }
   overflow-x: auto;
   scrollbar-width: thin;
 }
+/* Fade the trailing edge so a tab scrolled out of view reads as "there is more"
+ * rather than as a label cut mid-word.  A mask rather than a colour-matched
+ * cover gradient: the card is transparent, so a cover would have to track the
+ * page background across both themes and all nine styles.  Only the trailing
+ * edge is faded, so the first tab stays crisp when the strip is at rest. */
+.tab-bar-nav {
+  -webkit-mask-image: linear-gradient(to right, #000 calc(100% - 2rem), transparent 100%);
+  mask-image: linear-gradient(to right, #000 calc(100% - 2rem), transparent 100%);
+}
 .tab-bar-nav::-webkit-scrollbar { height: 3px; }
 .tab-bar-nav::-webkit-scrollbar-thumb {
   border-radius: 3px;