fix(design): claim audit part 1b — whole-row switches, the field-family edge, state-layer hovers, icon links, reason-disabled controls, 24/44 targets (E28)

- F12 (owner: A): SwitchRow, the whole settings row toggles; a Config boolean toggles from its title
  and hint (a label pointed at the switch).
- F14 (owner: B): the form dropdown trigger wears the field frame (see-through, the >= 3:1 edge);
  labelled pills keep the faint edge and the accent-edge hover. DESIGN says so, with log rows.
- F6: ~15 bg-card / bg-border / opacity hovers onto the B3 state layer; a lint rule (HOVER_SWAP)
  refuses the swap, contract-tested.
- F10: bare 14px icon links onto IconLink / LinkButton; a local lint rule refuses a glyph-only <a>.
- F13: reason-disabled controls are aria-disabled (Users, Channels backfill, Discovery, Scheduler
  runs, Config tests); FocusSafeButton now swallows the click of a caller's aria-disabled; the
  Config tests say why while dirty (testDirty, HU/EN).
- F5/F11: every control measured live at 24 (mouse) and 44 (coarse) across every page; touch-target
  is a utility that wins over a caller's min-h-6; link variants carry it too; SegmentedToggle,
  Tabs, NavRail, menu rows, PriorityStepper, sliders, CheckRow, InnerInput, card links and the rest.
- F9: DismissibleChip's label reaches the chip's 24; the Combobox chips are DismissibleChips.
- F15: the "+N" / "More..." open state worded as it renders.

frontend/src/components/ui/Button.dom.test.tsx

@@ -156,17 +156,18 @@ describe("Button primitive (S5)", () => {
     }
   });
 
-  it("carries the coarse-pointer minimum target, except on a link", () => {
+  it("carries the coarse-pointer minimum target and the 24 floor, a link variant too", () => {
     // The tablet comfort contract: the minimum lives in the primitive, so no call site can opt
-    // out of it by accident. A link is text in a sentence and is excluded by design.
+    // out of it by accident. A link variant was once excluded as "text in a sentence", but every
+    // one stands alone, and the E28 audit measured them at 16–20px.
     const { unmount } = render(<Button>Tap</Button>);
     expect(screen.getByRole("button", { name: "Tap" }).className).toContain("touch-target");
     unmount();
     for (const variant of ["link", "link-muted"] as const) {
       const { unmount: u } = render(<Button variant={variant}>Read more</Button>);
-      expect(screen.getByRole("button", { name: "Read more" }).className).not.toContain(
-        "touch-target",
-      );
+      const cls = screen.getByRole("button", { name: "Read more" }).className;
+      expect(cls).toContain("touch-target");
+      expect(cls).toContain("min-h-6");
       u();
     }
   });
@@ -223,6 +224,20 @@ describe("Button · disabled while it holds the focus", () => {
     active.mockRestore();
   });
 
+  it("keeps a caller's aria-disabled focusable and inert to a click (unavailable with a reason)", () => {
+    const onClick = vi.fn();
+    render(
+      <Button onClick={onClick} aria-disabled>
+        Run all
+      </Button>,
+    );
+    const btn = screen.getByRole("button", { name: "Run all" });
+    expect(btn.hasAttribute("disabled")).toBe(false);
+    expect(btn.getAttribute("aria-disabled")).toBe("true");
+    fireEvent.click(btn);
+    expect(onClick).not.toHaveBeenCalled();
+  });
+
   it("is natively disabled again once the focus is elsewhere", () => {
     render(
       <Button onClick={() => {}} disabled>