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.ts

@@ -61,6 +61,11 @@ export interface WorkflowStatus {
   requiresReason: boolean;
   /** Archived: no new tickets or transitions into it; existing ones keep it. */
   archived: boolean;
+  /**
+   * Work-in-progress limit: how many tickets the column should hold at most
+   * (null: no limit). A warning, not a lock: the board flags a full column.
+   */
+  wipLimit?: number | null;
 }
 
 export interface IssueTypeOption {
@@ -193,6 +198,11 @@ export class ProjectWorkflow {
     return this.settings.statuses.find((s) => s.id === id);
   }
 
+  /** Most tickets the status should hold (null: no limit). */
+  wipLimit(id: string): number | null {
+    return this.status(id)?.wipLimit ?? null;
+  }
+
   /** Name to show, also for ids no longer configured. */
   statusName(id: string): string {
     return (
@@ -287,6 +297,8 @@ export function validateProjectSettings(
     color: s.color,
     requiresReason: !!s.requiresReason,
     archived: !!s.archived,
+    // Only when set: settings saved unchanged must compare equal.
+    ...(s.wipLimit != null ? { wipLimit: s.wipLimit } : {}),
   }));
   const issueTypes = next.issueTypes.map((t) => ({
     id: normId(t.id),
@@ -326,6 +338,11 @@ export function validateProjectSettings(
       SETTING_COLORS.includes(s.color),
       `Color no válido en el estado ${s.name}`,
     );
+    assertThat(
+      s.wipLimit === undefined ||
+        (Number.isInteger(s.wipLimit) && s.wipLimit >= 1 && s.wipLimit <= 999),
+      `El límite WIP del estado ${s.name} tiene que ser un número entre 1 y 999`,
+    );
   }
   for (const t of issueTypes) {
     assertThat(