chore(release): redesign UI tokens and publish styles 0.8.26, ui 0.8.86

Visual-only redesign ("instrument panel"): cool graphite neutrals for light
and dark, layered hairline elevation, larger radii, a mono token for
eyebrows/data, keycap-style solid and secondary buttons, recessed input
wells and tab tracks, a stronger dialog, and a theme-driven focus outline.
No props, outputs or behaviour change.

Also records the already-published csr 0.8.42, styles 0.8.25 and ui 0.8.85
changes (optional chaining/nullish in the reactive runtime, shared
theme/accent cookie sync, BackToTop hidden attribute).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/ui/components/Tabs.wrn

@@ -223,7 +223,9 @@ component Tabs {
       padding: 0.25rem;
       border: 1px solid var(--wrn-color-border);
       border-radius: var(--wrn-radius-md);
-      background: var(--wrn-color-surface-soft);
+      background: var(--wrn-color-surface-muted, var(--wrn-color-surface-soft));
+      /* Recessed track; the selected tab sits proud of it like a keycap. */
+      box-shadow: inset 0 1px 2px rgb(0 0 0 / 0.05);
       /* A long tablist scrolls rather than wrapping into an unusable stack. */
       overflow-x: auto;
     }
@@ -279,7 +281,9 @@ component Tabs {
       background: var(--wrn-color-surface);
       /* Small text on the accent alone misses 4.5:1, so it blends toward the text colour. */
       color: color-mix(in srgb, var(--tabs-accent) 72%, var(--wrn-color-text));
-      box-shadow: var(--wrn-shadow-1);
+      box-shadow:
+        0 0 0 1px color-mix(in srgb, var(--wrn-color-border) 80%, transparent),
+        var(--wrn-shadow-1);
     }
 
     .wrn-tabs__tab[aria-disabled="true"] {