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/styles/test/shared-preferences.test.ts

@@ -0,0 +1,58 @@
+import { expect, test } from "bun:test";
+import { Browser } from "happy-dom";
+import { renderThemeRuntime, resolveThemeConfig } from "../src/theme.ts";
+
+test("shared preferences replace stale host cookies and update another open app", async () => {
+  const browser = new Browser({ settings: { disableCSSFileLoading: true } });
+  try {
+    const first = browser.newPage();
+    first.url = "https://account.example.com/";
+    const second = browser.newPage();
+    second.url = "https://link.example.com/";
+    const a = first.mainFrame.window;
+    const b = second.mainFrame.window;
+    // Happy DOM coalesces equal-name host/domain cookies. Model their distinct
+    // browser storage keys so the legacy-shadow migration is exercised.
+    const jar = new Map<string, { name: string; value: string; domain: string; hostOnly: boolean }>();
+    function cookies(win: typeof a) {
+      Object.defineProperty(win.document, "cookie", {
+        get() { return [...jar.values()].filter(c => c.hostOnly ? c.domain === win.location.hostname : win.location.hostname === c.domain || win.location.hostname.endsWith("." + c.domain)).map(c => `${c.name}=${c.value}`).join("; "); },
+        set(raw: string) {
+          const [pair, ...options] = raw.split(";");
+          const split = pair!.indexOf("=");
+          const name = pair!.slice(0, split), value = pair!.slice(split + 1);
+          const domainOption = options.find(v => v.trim().toLowerCase().startsWith("domain="));
+          const domain = domainOption ? domainOption.trim().slice(7).replace(/^\./, "") : win.location.hostname;
+          const key = `${name}|${domain}`;
+          if(options.some(v => v.trim().toLowerCase() === "max-age=0")) jar.delete(key);
+          else jar.set(key, { name, value, domain, hostOnly: !domainOption });
+        },
+      });
+    }
+    cookies(a); cookies(b);
+    a.document.cookie = "wrn-theme=light;path=/";
+    b.document.cookie = "wrn-theme=light;path=/";
+    a.document.cookie = "wrn-theme=dark;path=/;domain=.example.com;secure";
+    a.document.cookie = "wrn-accent=rose;path=/;domain=.example.com;secure";
+    const js = renderThemeRuntime(resolveThemeConfig({ palette: "emerald" }, { defaults: { domain: ".example.com", secure: true } }));
+    for (const win of [a, b]) {
+      win.document.documentElement.setAttribute("data-theme", "light");
+      win.document.documentElement.setAttribute("data-accent", "emerald");
+      win.eval(js);
+      expect(win.document.documentElement.getAttribute("data-theme")).toBe("dark");
+      expect(win.document.cookie.match(/wrn-theme=/g)?.length).toBe(1);
+    }
+    a.eval('wrnTheme.set("light");wrnAccent.set("violet");wrnCookies.set("wrn-lang","hi","language")');
+    expect(b.document.cookie).toContain("wrn-theme-mode=manual");
+    b.dispatchEvent(new b.Event("focus"));
+    expect(b.document.documentElement.getAttribute("data-theme")).toBe("light");
+    expect(b.document.documentElement.getAttribute("data-accent")).toBe("violet");
+    expect(b.document.cookie).toContain("wrn-lang=hi");
+    a.eval('wrnTheme.followSystem()');
+    expect(b.document.cookie).toContain("wrn-theme-mode=system");
+    const outsider = browser.newPage();
+    outsider.url = "https://unrelated.example.net/";
+    cookies(outsider.mainFrame.window);
+    expect(outsider.mainFrame.window.document.cookie).toBe("");
+  } finally { await browser.close(); }
+});