refactor: enhance TimerPage layout and functionality; update theme and tokens for improved design consistency

- Refactored TimerPage component to improve layout and user experience.
- Updated theme configuration to utilize design tokens for better maintainability.
- Introduced new tokens for colors and typography to align with design principles.
- Simplified state management and improved timer functionality.
- Enhanced accessibility and responsiveness of UI elements.

backend/tests/test_api.py

@@ -24,9 +24,6 @@ def test_a_whole_pomodoro_through_the_api(client):
     assert done["finished"]["status"] == "completed"
     assert done["completed_today"] == 1
 
-    marked = client.post(f"/api/tasks/{task['id']}/done", json={"done": True}).json()
-    assert marked["task"]["is_done"] is True
-
     report = client.get("/api/reports/daily").json()
     assert report["report"]["metrics"]["pomodoros"] == 1
     assert "Daily report" in report["telegram_preview"]
@@ -37,6 +34,18 @@ def test_timer_errors_are_400_not_500(client):
     assert client.post("/api/timer/complete", json={}).status_code == 400
 
 
+def test_tasks_cannot_be_ticked_off_here(client):
+    """Completion belongs to Jira / Todoist / Google — we only notice it.
+
+    405 rather than 404 because the SPA catch-all claims unknown paths for GET;
+    either way there is no way to close a task through the API.
+    """
+    task = client.post("/api/tasks", json={"title": "Not yours to close"}).json()
+    response = client.post(f"/api/tasks/{task['id']}/done", json={"done": True})
+    assert response.status_code in (404, 405)
+    assert client.get("/api/tasks").json()["tasks"][0]["is_done"] is False
+
+
 def test_task_crud(client):
     created = client.post("/api/tasks", json={"title": "Temporary", "priority": "p2"}).json()
     listing = client.get("/api/tasks").json()