feat: tickets I follow, and more news for followers

"Que sigo" on the home page lists the open tickets I follow, whoever
works on them; `watching` filters my issues (REST, GraphQL, MCP) and a
project's search (none without a session).

Followers now also hear when a ticket's priority or due date changes,
and when it enters or leaves a sprint. Smaller edits (title, labels…)
still do not notify.

Docs (with the REPLIED row the replies change missed), Word and PDF
updated.

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

libs/web/tracker/application/src/lib/facades/home.facade.ts

@@ -18,6 +18,9 @@ export class HomeFacade {
   /** Tickets of my projects in a QA-category status (anyone's). */
   readonly awaitingQa = this.store.awaitingQa;
   readonly awaitingQaTotal = this.store.awaitingQaTotal;
+  /** Open tickets I follow, whoever works on them. */
+  readonly following = this.store.following;
+  readonly followingTotal = this.store.followingTotal;
   /** Planned releases of my projects, soonest first. */
   readonly releases = this.store.releases;
   /** False until the first load: show skeletons, not empty states. */