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/web/tracker/application/src/lib/facades/issue.facade.ts

@@ -231,6 +231,22 @@ export class IssueFacade {
     this.dispatch.reactRequested({ commentId, emoji, on });
   }
 
+  /**
+   * Settles a conversation (or reopens it); a conclusion is added as a
+   * reply marked as a decision.
+   */
+  resolveThread(
+    commentId: string,
+    resolved: boolean,
+    conclusion: string | null = null,
+  ): void {
+    this.dispatch.threadResolveRequested({
+      commentId,
+      resolved,
+      conclusion: conclusion?.trim() || null,
+    });
+  }
+
   /** Marks a comment as a decision of the ticket (`on`) or unmarks it. */
   markDecision(commentId: string, on: boolean): void {
     this.dispatch.decisionRequested({ commentId, on });