WIP: Add multiplayer Snake game

N-player (2-8) real-time Snake game alongside Connect 4.
Lobby has tabs to switch between games. Players join via
invite link with 10-second countdown. Game loop runs at
tick-based intervals with NATS pub/sub for state sync.

Keyboard input not yet working (Datastar keydown binding
issue still under investigation).

ui/snakelobby.go

@@ -0,0 +1,74 @@
+package ui
+
+import (
+	"fmt"
+
+	"github.com/ryanhamamura/c4/snake"
+	"github.com/ryanhamamura/via/h"
+)
+
+func SnakeLobbyTab(nicknameBind h.H, presetClicks []h.H, activeGames []*snake.SnakeGame) h.H {
+	var presetButtons []h.H
+	for i, preset := range snake.GridPresets {
+		var click h.H
+		if i < len(presetClicks) {
+			click = presetClicks[i]
+		}
+		presetButtons = append(presetButtons,
+			h.Button(
+				h.Class("btn btn-primary"),
+				h.Type("button"),
+				h.Text(fmt.Sprintf("%s (%d×%d)", preset.Name, preset.Width, preset.Height)),
+				click,
+			),
+		)
+	}
+
+	createSection := h.Div(h.Class("mb-6"),
+		h.H3(h.Class("text-lg font-bold mb-2"), h.Text("Create Game")),
+		h.Div(h.Class("mb-4"),
+			h.FieldSet(h.Class("fieldset"),
+				h.Label(h.Class("label"), h.Text("Your Nickname"), h.Attr("for", "snake-nickname")),
+				h.Input(
+					h.Class("input input-bordered w-full"),
+					h.ID("snake-nickname"),
+					h.Type("text"),
+					h.Placeholder("Enter your nickname"),
+					nicknameBind,
+					h.Attr("required"),
+				),
+			),
+		),
+		h.Div(append([]h.H{h.Class("flex gap-2 justify-center")}, presetButtons...)...),
+	)
+
+	var gameListEl h.H
+	if len(activeGames) > 0 {
+		var items []h.H
+		for _, g := range activeGames {
+			playerCount := g.PlayerCount()
+			sizeLabel := fmt.Sprintf("%d×%d", g.State.Width, g.State.Height)
+			statusLabel := "Waiting"
+			if g.Status == snake.StatusCountdown {
+				statusLabel = "Starting soon"
+			}
+			items = append(items, h.A(
+				h.Href("/snake/"+g.ID),
+				h.Class("flex justify-between items-center p-3 bg-base-200 rounded-lg hover:bg-base-300 no-underline text-base-content"),
+				h.Span(h.Text(fmt.Sprintf("%s — %d/8 players", sizeLabel, playerCount))),
+				h.Span(h.Class("text-sm opacity-60"), h.Text(statusLabel)),
+			))
+		}
+		listAttrs := []h.H{h.Class("flex flex-col gap-2")}
+		listAttrs = append(listAttrs, items...)
+		gameListEl = h.Div(h.Class("mt-6"),
+			h.H3(h.Class("text-lg font-bold mb-2 text-center"), h.Text("Join a Game")),
+			h.Div(listAttrs...),
+		)
+	}
+
+	return h.Div(
+		createSection,
+		gameListEl,
+	)
+}