feat: conversations on a ticket are settled, and you see who is typing

A top-level comment and its replies can be resolved by whoever can
change the ticket (CommentThreadResolvedEvent), with an optional
conclusion added as a reply marked as a decision, so it shows above the
ticket. A settled conversation folds to one line (topic, who settled it
and the conclusion) and can be unfolded or reopened; the header counts
the open ones, and finishing the ticket with one open asks first.

«Ana está escribiendo…» shows in the conversation being answered, at
once: a `typing` mutation publishes to a Redis channel per ticket
(`typing` subscription), never stored. In replies, Enter sends and
Shift+Enter breaks the line, except inside lists and code.

API: resolveThread / PUT-DELETE /api/comments/{id}/resolution, Comment
.resolved/resolvedBy/resolvedAt, typing mutation and subscription. MCP:
resolve_thread.

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

libs/api/tracker/domain/src/lib/read-models/comment.read-model.ts

@@ -26,6 +26,11 @@ export class CommentReadModel {
   /** Who marked it and when (null when it is not a decision). */
   decidedBy!: UserRefReadModel | null;
   decidedAt!: string | null;
+  /** A top-level comment whose conversation was settled. */
+  resolved!: boolean;
+  /** Who settled it and when (null while open). */
+  resolvedBy!: UserRefReadModel | null;
+  resolvedAt!: string | null;
   createdAt!: string;
   editedAt!: string | null;
   version!: number;