feat(game): official first-move tile draw + admin step-by-step replay

Decide who moves first by the official rule: each seated player draws one
tile, the one closest to "A" leads (a blank beats every letter), ties
re-drawing until a single leader remains. Each draw uses honest per-draw
crypto/rand entropy (not the deterministic bag seed), so the recorded draw —
not a seed — is the only account of the outcome. The leader takes seat 0, so
the engine and journal replay are unchanged.

The draw is recorded with the game (game_setup_draws, migration 00013) for
future tournaments, designed as a discrete "player N draws a tile" step.
Friend/AI games draw at creation. Auto-match draws when the game opens,
against a synthetic uuid.Nil opponent whose draw rows (NULL account_id) are
back-filled to the real opponent on join — so the opener's seat is fixed up
front and the existing open-game pre-move is preserved with no reseating.

Admin /_gm/games/:id gains the recorded draw list and a simple step-by-step
board replay (game.ReplayTimeline + a vanilla-JS stepper): a board with
A-O/1-15 headers and highlighted premium squares, placed letters with their
tile value as a subscript, rack panels around the board (seat 0 top, 1
bottom, 2 left, 3 right) with the current player highlighted, and a per-move
log with the tiles drawn and the bag remainder.

Docs: ARCHITECTURE §6/§9, FUNCTIONAL (+_ru), PRERELEASE (FM row), design spec.

backend/internal/server/handlers_admin_console.go

@@ -523,6 +523,34 @@ func (s *Server) consoleGameDetail(c *gin.Context) {
 			}
 		}
 	}
+	// First-move draw (docs/ARCHITECTURE.md §6) and the step-by-step replay timeline. Both are
+	// best-effort: a game that predates the draw or cannot be replayed still renders its
+	// summary and seats.
+	names := make(map[string]string, len(view.Seats))
+	for _, st := range view.Seats {
+		names[st.AccountID] = st.DisplayName
+	}
+	if draws, derr := s.games.SetupDraws(ctx, g.ID); derr == nil {
+		for _, d := range draws {
+			row := adminconsole.SetupDrawRow{Round: d.Round, Letter: strings.ToUpper(d.Letter), Blank: d.Blank, Rank: d.Rank}
+			if d.Account == uuid.Nil {
+				row.Name = "(opponent)"
+			} else {
+				row.Name = names[d.Account.String()]
+				row.AccountID = d.Account.String()
+			}
+			view.SetupDraws = append(view.SetupDraws, row)
+		}
+	}
+	if len(view.Seats) > 0 {
+		view.FirstMover = view.Seats[0].DisplayName
+	}
+	if tl, terr := s.games.ReplayTimeline(ctx, g.ID); terr == nil {
+		if rj, jerr := buildReplayJSON(g.Variant, tl, view.Seats); jerr == nil {
+			view.ReplayJSON = rj
+			view.HasReplay = len(tl.Steps) > 0
+		}
+	}
 	s.renderConsole(c, "game_detail", "games", "Game", view)
 }