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/profile.go

@@ -0,0 +1,110 @@
+package main
+
+import (
+	"github.com/ryanhamamura/via"
+	"github.com/ryanhamamura/via/h"
+)
+
+func ProfilePage(c *via.Context) {
+	existingName := c.Session().GetString(SessionKeyUsername)
+	existingEmoji := c.Session().GetString(SessionKeyEmoji)
+	if existingEmoji == "" {
+		existingEmoji = emojiChoices[0]
+	}
+
+	nameField := c.Field(existingName,
+		via.Required("Display name is required"),
+		via.MinLen(2, "Must be at least 2 characters"),
+		via.MaxLen(20, "Must be at most 20 characters"),
+	)
+	selectedEmoji := c.Signal(existingEmoji)
+
+	saveToSession := func() bool {
+		if !c.ValidateAll() {
+			c.Sync()
+			return false
+		}
+		c.Session().Set(SessionKeyUsername, nameField.String())
+		c.Session().Set(SessionKeyEmoji, selectedEmoji.String())
+		return true
+	}
+
+	save := c.Action(func() {
+		saveToSession()
+	})
+
+	saveAndChat := c.Action(func() {
+		if saveToSession() {
+			c.Navigate("/", false)
+		}
+	})
+
+	c.View(func() h.H {
+		// Emoji grid
+		emojiGrid := []h.H{h.Class("emoji-grid")}
+		for _, emoji := range emojiChoices {
+			cls := "emoji-option"
+			if emoji == selectedEmoji.String() {
+				cls += " emoji-selected"
+			}
+			emojiGrid = append(emojiGrid,
+				h.Button(
+					h.Class(cls),
+					h.Type("button"),
+					h.Text(emoji),
+					save.OnClick(WithSignal(selectedEmoji, emoji)),
+				),
+			)
+		}
+
+		// Action buttons — "Start Chatting" only if editing is meaningful
+		actionButtons := []h.H{h.Class("profile-actions")}
+		if existingName != "" {
+			actionButtons = append(actionButtons,
+				h.Button(h.Text("Save"), save.OnClick(), h.Class("secondary")),
+			)
+		}
+		actionButtons = append(actionButtons,
+			h.Button(h.Text("Start Chatting"), saveAndChat.OnClick()),
+		)
+
+		previewName := nameField.String()
+		if previewName == "" {
+			previewName = "Your Name"
+		}
+
+		return h.Div(h.Class("profile-page"),
+			h.H2(h.Text("Your Profile"), h.DataViewTransition("page-title")),
+
+			// Live preview
+			h.Div(h.Class("profile-preview"),
+				h.Div(h.Class("avatar avatar-lg"), h.Text(selectedEmoji.String())),
+				h.Span(h.Class("preview-name"), h.Text(previewName)),
+			),
+
+			h.Div(h.Class("profile-form"),
+				// Name field
+				h.Label(h.Text("Display Name"),
+					h.Input(
+						h.Type("text"),
+						h.Placeholder("Enter a display name"),
+						nameField.Bind(),
+						h.Attr("autofocus"),
+						saveAndChat.OnKeyDown("Enter"),
+						h.If(nameField.HasError(), h.Attr("aria-invalid", "true")),
+					),
+					h.If(nameField.HasError(),
+						h.Small(h.Class("field-error"), h.Text(nameField.FirstError())),
+					),
+				),
+
+				// Emoji picker
+				h.Label(h.Text("Choose an Avatar")),
+				h.Div(emojiGrid...),
+
+				// Actions
+				h.Div(actionButtons...),
+			),
+		)
+	})
+}