feat: work-in-progress limits and swimlanes on the board

Each status can carry a WIP limit in the project settings; the board shows
it next to the count, marks a column that goes over it and says so when a
card is dropped there. The board can also be grouped in rows by person,
epic, priority or type, remembered per browser.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

libs/api/tracker/domain/src/lib/project/project-settings.spec.ts

@@ -99,6 +99,23 @@ describe('Project settings', () => {
     );
   });
 
+  it('keeps work-in-progress limits, from 1 to 999', () => {
+    const project = newProject();
+    const limited = defaultProjectSettings();
+    limited.statuses[2].wipLimit = 3;
+    project.updateSettings('owner', limited);
+    expect(project.workflow.wipLimit(limited.statuses[2].id)).toBe(3);
+    expect(project.workflow.wipLimit('TODO')).toBeNull();
+    // Saving the same again is no change.
+    const before = project.getUncommittedEvents().length;
+    project.updateSettings('owner', structuredClone(limited));
+    expect(project.getUncommittedEvents()).toHaveLength(before);
+
+    const zero = defaultProjectSettings();
+    zero.statuses[2].wipLimit = 0;
+    expect(() => project.updateSettings('owner', zero)).toThrow(/WIP/);
+  });
+
   it('rejects settings that would break the board', () => {
     const project = newProject();
     const noStart = defaultProjectSettings();