feat: quick polls in comments that end in a decision

«📊 Añadir una encuesta» adds 2 to 6 options to a new comment. Members,
viewers too, vote by clicking an option (one vote each, which they can
change or take back) and see each option's votes as a bar. Whoever
started it, or an admin, closes it with «Cerrar y decidir»: the most
voted wins (none on a tie) and a «Decidido: …» reply marked as a
decision shows above the ticket. Events of the comment (voted, closed).

API: addComment(…, poll), votePoll, closePoll, Comment.poll;
POST /api/comments/{id}/poll/vote and …/poll/close. MCP: add_comment
poll, vote_poll, close_poll.

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

libs/web/tracker/infrastructure/src/lib/graphql/fragments.graphql

@@ -204,6 +204,16 @@ fragment CommentFields on Comment {
   decidedBy {
     ...UserRefFields
   }
+  poll {
+    options {
+      text
+      voters {
+        ...UserRefFields
+      }
+    }
+    closed
+    winner
+  }
   resolved
   resolvedBy {
     ...UserRefFields