mobile: per-view ≤480px rules across the CSS bundle

Adds the @media (max-width: 480px) blocks specified in the design:

- dashboard.css: indicator table hides the 'mobile-hide'-tagged
  columns (Label, Ccy, 1y, anchor, as-of), keeping Symbol / Price /
  1d / 1m. Cell padding + font shrink. Group-tab buttons get a
  bigger touch target.
- panels.css: header padding tightens, scroll-body max-height drops
  to 60vh so log/news stay above the fold in the stacked layout.
- portfolio.css: overall grid keeps 2 cols (already at 640px) with
  tighter gap; action buttons wrap; composer input goes full-width.
- log-chat.css: chat bubbles edge-to-edge, input row stacks, font-
  size:14px on form fields to avoid iOS Safari zoom-on-focus.
- news.css: row collapses to age | (title / source) — source moves
  under the title. Tag filter strip wraps.
- settings.css: form rows stack (label above input). Import picker
  becomes single-column. Buttons full-width.
- auth.css: card padding tightens to free up vertical space when the
  iOS keyboard is up. font-size:14px on inputs.
- public.css: hero headline clamp() lower bound drops to 22px; CTAs
  stack full-width; pricing tier-grid stacks.

indicators.html: tagged the secondary cells with .mobile-hide rather
than relying on positional nth-child — the anchor column is
conditional and would have shifted positions.

336 tests still pass.

app/static/css/public.css

@@ -715,3 +715,29 @@ a.btn-secondary:hover { color: var(--accent); border-color: var(--accent); }
   color: var(--accent);
   outline: none;
 }
+
+
+/* --- Mobile (≤480px) -------------------------------------------------- */
+
+@media (max-width: 480px) {
+  /* Hero headline already uses clamp(); shrink its lower bound so a
+     two-line headline doesn't push the CTAs below the fold on a
+     360px screen. */
+  .hero__headline { font-size: clamp(22px, 6vw, 32px); }
+  .hero__subhead { font-size: 14px; }
+
+  /* CTAs stack full-width on phones — easier tap targets. */
+  .hero__ctas { flex-direction: column; align-items: stretch; }
+  .btn-primary, .btn-secondary {
+    width: 100%;
+    text-align: center;
+    padding: 12px 18px;
+  }
+
+  /* Tier cards (pricing page) stack on phones. */
+  .tier-grid { grid-template-columns: 1fr; gap: 16px; }
+  .tier-card { padding: 18px; }
+
+  /* Tighten public-page outer padding. */
+  .public-shell { padding: 16px 12px; }
+}