feat: comments marked as decisions, on top of the ticket and searchable

Whoever can change the ticket flags a comment as a decision (new event
CommentDecisionMarkedEvent on the comment). The ticket page lists its
decisions above the description, with a link to the comment in the
conversation (`?comment=<id>` scrolls to it and points at it), and the
search palette finds them by their text across my projects.

API: markDecision / PUT-DELETE /api/comments/{id}/decision; Issue.decisions
and GET /api/issues/{issue}/decisions; decisions(projectId?, search) and
GET /api/projects/{project}/decisions, GET /api/me/decisions. MCP:
mark_decision, search_decisions, and get_issue includes them.

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

libs/web/tracker/application/src/lib/events/issue.events.ts

@@ -71,6 +71,7 @@ export const issuePageEvents = eventGroup({
     }>(),
     commentEditRequested: type<{ commentId: string; body: string }>(),
     reactRequested: type<{ commentId: string; emoji: string; on: boolean }>(),
+    decisionRequested: type<{ commentId: string; on: boolean }>(),
     voteRequested: type<{ issueId: string; on: boolean }>(),
     /** An image pasted into a text was uploaded (it joins the ticket's files). */
     imagePasted: type<{ issueId: string }>(),