refactor: split nats-chatroom into modules with profile, layout, and auth

Extract chat, profile, types, and user data into separate files.
Embed CSS via go:embed. Add a layout with nav, session-based profile
persistence, and a middleware guard that redirects to /profile when
no identity is set.

internal/examples/nats-chatroom/chat.go

@@ -0,0 +1,148 @@
+package main
+
+import (
+	"sync"
+	"time"
+
+	"github.com/ryanhamamura/via"
+	"github.com/ryanhamamura/via/h"
+)
+
+var (
+	WithSignal = via.WithSignal
+)
+
+func ChatPage(c *via.Context) {
+	currentUser := UserInfo{
+		Name:  c.Session().GetString(SessionKeyUsername),
+		Emoji: c.Session().GetString(SessionKeyEmoji),
+	}
+
+	roomSignal := c.Signal("Go")
+	statement := c.Signal("")
+
+	var messages []ChatMessage
+	var messagesMu sync.Mutex
+	currentRoom := "Go"
+
+	var currentSub via.Subscription
+
+	subscribeToRoom := func(room string) {
+		if currentSub != nil {
+			currentSub.Unsubscribe()
+		}
+
+		subject := "chat.room." + room
+
+		if hist, err := via.ReplayHistory[ChatMessage](v, subject, 50); err == nil {
+			messages = hist
+		}
+
+		sub, _ := via.Subscribe(c, subject, func(msg ChatMessage) {
+			messagesMu.Lock()
+			messages = append(messages, msg)
+			if len(messages) > 50 {
+				messages = messages[len(messages)-50:]
+			}
+			messagesMu.Unlock()
+			c.Sync()
+		})
+		currentSub = sub
+		currentRoom = room
+	}
+
+	subscribeToRoom("Go")
+
+	// Heartbeat — keeps connected indicator alive
+	connected := true
+	c.OnInterval(30*time.Second, func() {
+		connected = true
+		c.Sync()
+	})
+
+	switchRoom := c.Action(func() {
+		newRoom := roomSignal.String()
+		if newRoom != currentRoom {
+			messagesMu.Lock()
+			messages = nil
+			messagesMu.Unlock()
+			subscribeToRoom(newRoom)
+			c.Sync()
+		}
+	})
+
+	say := c.Action(func() {
+		msg := statement.String()
+		if msg == "" {
+			msg = randomDevQuote()
+		}
+		statement.SetValue("")
+
+		via.Publish(c, "chat.room."+currentRoom, ChatMessage{
+			User:    currentUser,
+			Message: msg,
+			Time:    time.Now().UnixMilli(),
+		})
+	})
+
+	c.View(func() h.H {
+		var tabs []h.H
+		for _, name := range roomNames {
+			isCurrent := name == currentRoom
+			tabs = append(tabs, h.Li(
+				h.A(
+					h.If(isCurrent, h.Attr("aria-current", "page")),
+					h.Text(name),
+					switchRoom.OnClick(WithSignal(roomSignal, name)),
+				),
+			))
+		}
+
+		messagesMu.Lock()
+		chatHistoryChildren := []h.H{
+			h.Class("chat-history"),
+			h.Script(h.Raw(`new MutationObserver(()=>scrollChatToBottom()).observe(document.querySelector('.chat-history'), {childList:true})`)),
+		}
+		for _, msg := range messages {
+			chatHistoryChildren = append(chatHistoryChildren,
+				h.Div(h.Class("chat-message"),
+					h.Div(h.Class("avatar"), h.Attr("title", msg.User.Name), h.Text(msg.User.Emoji)),
+					h.Div(h.Class("bubble"),
+						h.P(h.Text(msg.Message)),
+					),
+				),
+			)
+		}
+		messagesMu.Unlock()
+
+		_ = connected
+
+		return h.Div(h.Class("chat-page"),
+			h.Nav(
+				h.Attr("role", "tab-control"),
+				h.Ul(tabs...),
+				h.Span(h.Class("nats-badge"),
+					h.Span(h.Class("status-dot")),
+					h.Text("NATS"),
+				),
+			),
+			h.Div(chatHistoryChildren...),
+			h.Div(
+				h.Class("chat-input"),
+				h.DataIgnoreMorph(),
+				currentUser.Avatar(),
+				h.FieldSet(
+					h.Attr("role", "group"),
+					h.Input(
+						h.Type("text"),
+						h.Placeholder(currentUser.Name+" says..."),
+						statement.Bind(),
+						h.Attr("autofocus"),
+						say.OnKeyDown("Enter"),
+					),
+					h.Button(h.Text("Send"), say.OnClick()),
+				),
+			),
+		)
+	})
+}