Mid-game invite links and a surprise-report slip

The masthead's room code is now a button: one click copies the /join
link, which seats newcomers in a waiting room and the gallery once the
boards flip. And a 🐞 report opens a two-question slip — what happened,
what was expected — that lands in feedback.jsonl beside the rooms with
the room code, move number, round, and rules rev attached, so any
surprise can be replayed to its exact moment.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015RCWSTnb1KYTPyL4GmhGnF

packages/web/src/net.svelte.ts

@@ -594,6 +594,11 @@ class Net {
     this.games = this.games.filter((g) => g.roomId !== roomId);
   }
 
+  /** A surprise report: the server pins it to the room and move number. */
+  sendFeedback(happened: string, expected: string): void {
+    this.send({ type: "feedback", happened, expected });
+  }
+
   requestTransferCode(): void {
     this.send({ type: "makeTransfer" });
   }