The look from the server's tokens, pinned; the frame and bar follow the page's theme

ui/tokens.css is no longer a hand copy that drifts: scripts/fetch-tokens.sh
takes the server's tokens.css at a git ref and tokens.lock.json pins it, as
fetch-cli.sh does for the CLI. build.rs reads the two themes' --bg and --border
out of it, so no colour is written in Rust. The content view reports the page's
theme by a navigation the app refuses (llembas-theme:<name>), and the window,
the title bar and the first-run page are painted in it and remember it.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src-tauri/src/theme_report.js

@@ -0,0 +1,44 @@
+// Run in the content view on every page it shows (an initialization script, before the page's
+// own scripts). It reports the theme the page is in -- the server sets `data-theme` and
+// `data-base` on <html> (base.html, then app.js:applyTheme when the reader switches) -- so the
+// app can paint the frame and the title bar in the same look.
+//
+// The report is a navigation to `llembas-theme:<base>`, which the app's navigation handler
+// (lib.rs:allowed) reads and refuses, so nothing loads and the page is not left. That is the
+// whole channel: the server's pages get no IPC, and this gives them none -- a page can say one
+// of two theme names, and nothing else. The base, not the theme's id: a custom theme on the
+// server is a handful of colours over `moria` or `shire`, and the base is the look the app has.
+(function () {
+  "use strict";
+  // Only the server's pages: the app's own first-run page is painted from the app's side.
+  if (window.top !== window) return;
+  if (location.protocol !== "http:" && location.protocol !== "https:") return;
+  if (location.hostname === "tauri.localhost") return;
+
+  var last = "";
+  function report() {
+    var root = document.documentElement;
+    if (!root) return;
+    var base = root.getAttribute("data-base") || root.getAttribute("data-theme") || "";
+    if (base !== "moria" && base !== "shire") return;
+    if (base === last) return;
+    last = base;
+    try {
+      location.assign("llembas-theme:" + base);
+    } catch (e) { /* refused, as intended */ }
+  }
+  function watch() {
+    var root = document.documentElement;
+    if (!root) return;
+    new MutationObserver(report).observe(root, {
+      attributes: true,
+      attributeFilter: ["data-theme", "data-base"]
+    });
+    report();
+  }
+  if (document.readyState === "loading") {
+    document.addEventListener("DOMContentLoaded", watch);
+  } else {
+    watch();
+  }
+})();