feat: enhance CI workflow and update webapp styles

- Added Node.js setup and webapp testing steps to the CI workflow for improved integration.
- Updated HTML to link multiple CSS files for better modularity and organization of styles.
- Removed deprecated `style.css` and introduced new CSS files for base styles, calendar, day detail, hints, markers, states, and duty list to enhance maintainability and readability.
- Implemented new styles for improved presentation of duty information and user interactions.
- Added unit tests for new API functions and contact link rendering to ensure functionality and reliability.

webapp/js/hints.test.js

@@ -1,10 +1,11 @@
 /**
  * Unit tests for getDutyMarkerRows and buildDutyItemTimePrefix logic.
  * Covers: sorting order preservation, idx=0 with total>1 and startSameDay.
+ * Also tests dismissHint helper.
  */
 
-import { describe, it, expect, beforeAll } from "vitest";
-import { getDutyMarkerRows } from "./hints.js";
+import { describe, it, expect, beforeAll, beforeEach, afterEach, vi } from "vitest";
+import { getDutyMarkerRows, dismissHint } from "./hints.js";
 
 const FROM = "from";
 const TO = "until";
@@ -124,3 +125,52 @@ describe("getDutyMarkerRows", () => {
     expect(rows[2].timePrefix).toContain("15:00");
   });
 });
+
+describe("dismissHint", () => {
+  beforeEach(() => {
+    vi.useFakeTimers();
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
+  it("removes visible class immediately and hides element after delay", () => {
+    const el = document.createElement("div");
+    el.classList.add("calendar-event-hint--visible");
+    el.hidden = false;
+    el.setAttribute("data-active", "1");
+
+    dismissHint(el);
+
+    expect(el.classList.contains("calendar-event-hint--visible")).toBe(false);
+    expect(el.hidden).toBe(false);
+
+    vi.advanceTimersByTime(150);
+
+    expect(el.hidden).toBe(true);
+    expect(el.hasAttribute("data-active")).toBe(false);
+  });
+
+  it("returns timeout id usable with clearTimeout", () => {
+    const el = document.createElement("div");
+    const id = dismissHint(el);
+    expect(id).toBeDefined();
+    clearTimeout(id);
+    vi.advanceTimersByTime(150);
+    expect(el.hidden).toBe(false);
+  });
+
+  it("calls afterHide callback after delay when provided", () => {
+    const el = document.createElement("div");
+    let called = false;
+    dismissHint(el, {
+      afterHide: () => {
+        called = true;
+      },
+    });
+    expect(called).toBe(false);
+    vi.advanceTimersByTime(150);
+    expect(called).toBe(true);
+  });
+});