fix(ui): a focused, disabled FocusSafeButton no longer lights up on hover

A FocusSafeButton that holds the focus is disabled by aria-disabled, not the native attribute, so
every hover gated on `:disabled` / `enabled:` alone still fired on it — the glass lift, the primary /
danger / warn dim, and eight `enabled:hover:` chains (saved views, the player's list buttons, the
undo toolbar). Measured on localdev: the Pager's Next, focused at the last page, now keeps its resting
border and shadow under the pointer. The CSS selectors and the chains also exclude
`[aria-disabled="true"]`, and a lint rule refuses a bare `enabled:hover:` from now on.

frontend/src/lib/controlRules.contract.test.ts

@@ -3,9 +3,9 @@ import { fileURLToPath } from "node:url";
 import { ESLint } from "eslint";
 import { describe, expect, it } from "vitest";
 
-// The canonical "FE control" row (CLAUDE.md) as a lint rule: no native <select>. Six had drifted in
-// before the rule existed. A selector that matches nothing looks exactly like a clean codebase, so
-// this pins that it fires.
+// Two lint rules about controls: no native <select> (the canonical "FE control" row in CLAUDE.md;
+// six had drifted in before the rule existed), and no hover gated on `enabled:` alone. A selector
+// that matches nothing looks exactly like a clean codebase, so this pins that each fires.
 const FRONTEND = fileURLToPath(new URL("../../", import.meta.url));
 
 async function refused(source: string): Promise<number> {
@@ -20,3 +20,23 @@ describe("a native select", () => {
     expect(await refused("export const B = () => <SegmentedToggle />;\n")).toBe(0);
   });
 });
+
+// `enabled:hover:` is blind to a focused FocusSafeButton (aria-disabled, not the native attribute),
+// which then lit up on hover as if a click would work.
+describe("a hover gated on `enabled:` alone", () => {
+  it("is refused; the aria-aware gate is not", async () => {
+    const eslint = new ESLint({ cwd: FRONTEND });
+    const lint = async (cls: string) =>
+      (
+        await eslint.lintText(
+          `export const c = "p-1 ${cls}:text-fg";
+`,
+          {
+            filePath: "src/components/__probe.tsx",
+          },
+        )
+      )[0]?.messages.filter((m) => m.message.startsWith("`enabled:hover:`")).length;
+    expect(await lint("enabled:hover")).toBe(1);
+    expect(await lint("enabled:not-aria-disabled:hover")).toBe(0);
+  });
+});