feat(t5): ein Tabs-Baustein für Listen, Einstellungen und Statistik (T5a A8)

- ui/tabs.tsx nur noch Variante segment: Leiste auf --muted, aktiver Tab
  mit Kartenfläche, fetter Schrift und 3-px-Balken in --primary-ink;
  44 px bei Touch, kompakt mit Maus; inaktive Schrift ≥ 6,27:1.
- ActiveHistoryTabs als Vorlage auf Tabs für 10 Listen (Pfeiltasten
  schalten direkt, Daten sind geladen), mit toolbar und heading.
- Einstellungen (Automatisierung, Benutzer & Rollen) und Statistik mit
  manueller Aktivierung: Pfeil bewegt den Fokus, Enter/Leertaste wählt;
  ?tab= über router.replace. TabSwitcher entfernt.
- Menüeinträge (Dropdown, Select) mit innerem Fokusring ≥ 3:1.
- Aufgaben: der Prioritätsfilter lädt die Liste jetzt neu (queryKey).
- Wächter: keine eigenen tablist/tab/tabpanel außerhalb ui/tabs.tsx.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

ApiCore-Frontend/src/styles/baukasten-guard.spec.ts

@@ -144,6 +144,15 @@ const RULES: GuardRule[] = [
       },
     ],
   },
+  // Task A8: one tabs kit for the whole app (spec 10.4, 10.7). Base UI draws role tablist, tab
+  // and tabpanel inside ui/tabs.tsx, so no source file writes them by hand and the list of
+  // exceptions stays empty.
+  {
+    id: "no role tablist, tab or tabpanel outside ui/tabs.tsx",
+    pattern: ownRole("role", "tab(?:list|panel)?"),
+    scope: "src/**/*.{ts,tsx}",
+    allow: [],
+  },
 ];
 
 const SCOPE_FILE: Record<GuardScope, RegExp> = {
@@ -206,6 +215,20 @@ describe("baukasten guard (spec 10.7)", () => {
     expect(users.map(({ file }) => file)).toEqual([]);
   });
 
+  it("TabSwitcher is gone (the settings pages use Tabs directly, spec 10.4)", () => {
+    expect(existsSync(join(SRC, "components", "tab-switcher.tsx"))).toBe(false);
+    const users = FILES.filter(({ text }) => /\bTabSwitcher\b|components\/tab-switcher/.test(text));
+    expect(users.map(({ file }) => file)).toEqual([]);
+  });
+
+  it("the tabs kit has one variant, segment (the line variant is gone)", () => {
+    const tabs = FILES.find(({ file }) => file === "src/components/ui/tabs.tsx")?.text ?? "";
+    expect(tabs).toMatch(/segment/);
+    expect(tabs).not.toMatch(/variant=line|\bline:/);
+    const lineUsers = FILES.filter(({ text }) => /<TabsList\b[^>]*variant=["'{]/.test(text));
+    expect(lineUsers.map(({ file }) => file)).toEqual([]);
+  });
+
   it("a list of CheckboxFields keeps neighbouring targets at least 4 px apart (spec 4.5)", () => {
     // `.map(… => <CheckboxField` (optionally inside an <li>) and the container opened before it.
     const lists = FILES.filter(({ file }) => file.endsWith(".tsx")).flatMap(({ file, text }) =>
@@ -287,6 +310,16 @@ describe("baukasten guard (spec 10.7)", () => {
     // The CheckboxField exemption ends with its own tag: a later element is caught again.
     expect(toggle.test('<CheckboxField label="A" />\n<input role="switch" />')).toBe(true);
     expect(checkbox.test('<CheckboxField label="A" /><span role="checkbox" />')).toBe(true);
+    const tabs = rule("no role tablist, tab or tabpanel outside ui/tabs.tsx").pattern;
+    expect(tabs.test('<div role="tablist" className="flex">')).toBe(true);
+    expect(tabs.test('<button type="button" role="tab" aria-selected={on}>')).toBe(true);
+    expect(tabs.test("<section role={'tabpanel'}>")).toBe(true);
+    expect(tabs.test('{ role: "tab" }')).toBe(true);
+    expect(tabs.test('<div role={wide ? "tablist" : undefined}>')).toBe(true);
+    expect(tabs.test('node.setAttribute("role", "tab")')).toBe(true);
+    expect(tabs.test('<Table role="table">')).toBe(false);
+    expect(tabs.test(`querySelector('[role="tab"]')`)).toBe(false);
+    expect(tabs.test('getAllByRole("tab")')).toBe(false);
     expect(rule("no text-white").pattern.test('"text-white/80"')).toBe(true);
     expect(rule("no gradient prop or gradient token").pattern.test("<PageHeader gradient=\"honey\" />")).toBe(true);
   });