feat: pinned tickets, at hand on the home page and in search

Each person pins up to 20 tickets from the ticket's page («Fijar»). They
show as a strip under the projects on the home page and in the search
palette before typing. Private and without history, like the views of
«my work» (Mongo `pinned_issues`); tickets in the trash or out of reach
are left out, and when the list is full the unreadable ones are dropped
first.

API: GET /api/me/pins, PUT/DELETE /api/issues/{issue}/pin; GraphQL
myPins, pinIssue, unpinIssue and Issue.pinned.

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

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

@@ -43,6 +43,7 @@ export const issuePageEvents = eventGroup({
       replyTo?: string | null;
     }>(),
     watchRequested: type<{ issueId: string; watching: boolean }>(),
+    pinRequested: type<{ issueId: string; pinned: boolean }>(),
     trashRequested: type<{ issueId: string; trashed: boolean }>(),
     /** Place the ticket under another one by its key (e.g. WEB-3); null: out. */
     parentRequested: type<{ issueId: string; parentKey: string | null }>(),