feat: a calendar to subscribe to, and the backlog's corners

- Each person can subscribe their dates in Google Calendar, Outlook or
  Apple Calendar: GET /api/calendar/{token}.ics (no session) brings
  their unfinished tickets with a due date (assigned or followed), the
  planned and running sprints and the planned releases of their
  projects, as all-day events linking to the web. The token is made,
  renewed or dropped under /me/calendar (and in GraphQL); in the web,
  from «Calendario» in «Mi trabajo».
- The backlog panel keeps the selected rows' background inside its
  rounded corners.

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

libs/api/tracker/infrastructure/src/lib/mongo/find.repositories.ts

@@ -266,6 +266,25 @@ export class MongoFindIssuesRepository extends FindIssuesRepository {
     return docs.map(issueFromDoc);
   }
 
+  async findDatedFor(
+    userId: string,
+    projectIds: string[],
+  ): Promise<IssueReadModel[]> {
+    if (projectIds.length === 0) return [];
+    const docs = await this.issues
+      .find({
+        projectId: { $in: projectIds },
+        dueDate: { $ne: null },
+        trashedAt: null,
+        statusCategory: { $nin: FINISHED },
+        $or: [{ 'assignee.id': userId }, { 'watchers.id': userId }],
+      })
+      .sort({ dueDate: 1 })
+      .limit(1000)
+      .lean<IssueDoc[]>();
+    return docs.map(issueFromDoc);
+  }
+
   async findByProject(projectId: string): Promise<IssueReadModel[]> {
     const docs = await this.issues
       .find({ projectId, trashedAt: null })