Put the bug report behind an always-available button.

The debug report was only reachable in DEBUG mode, which is the one mode
a player hitting a real bug won't be running. Move it to a "🐛 Report a
bug" item in the game menu: a note field, a download, and a copy-as-text,
on any server.

That knowingly shows the reporter their opponents' hands and the shop
deck order. Credentials are still required, so a report only ever reaches
someone seated at that table. The buy-any-card panel stays DEBUG-only —
it changes the game; a report only reads it.

internal/game/debug.go

@@ -19,9 +19,10 @@ import (
 // work out which effect misfired. Report.Text() ends with a paste-ready test.
 //
 // Both forms contain hidden information — opponents' decks, the order of the
-// shop decks — so a report is an operator's artifact, not a player's. The
-// server only serves one in DEBUG mode; `go run ./cmd/report` pulls one out of
-// the database with no such gate, because by then you are the operator.
+// shop decks — and that is an accepted trade: the in-game "Report a bug" button
+// hands a player their own report on any server, DEBUG or not, because a bug
+// nobody can reproduce costs more than the little a cheat would gain.
+// `go run ./cmd/report` reads the same report out of the database.
 
 // DebugReportVersion is the report format's version, so an old report found on
 // disk can be recognized for what it is.