feat(15-02): create app_layout.templ and app_layout_helpers.go with sidebar sub-components

- Create backend/templates/app_layout_helpers.go: sidebarNavItem struct, sidebarNavItemClass, isActivePath, sidebarNavItemID, sidebarPrimaryNavItems
- Create backend/templates/app_layout.templ: SidebarNavIcon, SidebarNavItemRow, SidebarProjectsSection, SidebarOrganizationFooter, DashboardSidebar, AppLayout
- templ generate and go build exit 0; all existing tests pass

backend/templates/app_layout.templ

@@ -0,0 +1,174 @@
+package templates
+
+import (
+	"backend/internal/auth"
+	"backend/internal/db/sqlc"
+	"backend/internal/web/ui"
+)
+
+// SidebarNavIcon renders the SVG icon for the given sidebar icon kind.
+// SVG paths ported verbatim from go-backend/internal/web/views/icons.templ SidebarIcon.
+templ SidebarNavIcon(kind string) {
+	switch kind {
+		case "panels":
+			<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true">
+				<rect width="18" height="18" x="3" y="3" rx="2"></rect>
+				<path d="M3 9h18"></path>
+				<path d="M9 21V9"></path>
+			</svg>
+		case "tasks":
+			<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true">
+				<rect x="3" y="5" width="6" height="6" rx="1"></rect>
+				<path d="m3 17 2 2 4-4"></path>
+				<path d="M13 6h8"></path>
+				<path d="M13 12h8"></path>
+				<path d="M13 18h8"></path>
+			</svg>
+		case "layers":
+			<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true">
+				<path d="m12.83 2.18a2 2 0 0 0-1.66 0L2.6 6.08a1 1 0 0 0 0 1.83l8.58 3.91a2 2 0 0 0 1.66 0l8.58-3.9a1 1 0 0 0 0-1.83Z"></path>
+				<path d="m22 17.65-9.17 4.16a2 2 0 0 1-1.66 0L2 17.65"></path>
+				<path d="m22 12.65-9.17 4.16a2 2 0 0 1-1.66 0L2 12.65"></path>
+			</svg>
+		case "planning":
+			<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true">
+				<rect width="18" height="18" x="3" y="3" rx="2"></rect>
+				<path d="M8 7v7"></path>
+				<path d="M12 7v4"></path>
+				<path d="M16 7v9"></path>
+			</svg>
+		case "chat":
+			<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true">
+				<path d="M7.9 20A9 9 0 1 0 4 16.1L2 22Z"></path>
+			</svg>
+		case "files":
+			<svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true">
+				<path d="M20 20a2 2 0 0 0 2-2V8a2 2 0 0 0-2-2h-7.9a2 2 0 0 1-1.69-.9L9.6 3.9A2 2 0 0 0 7.93 3H4a2 2 0 0 0-2 2v13a2 2 0 0 0 2 2Z"></path>
+			</svg>
+		default:
+			<span></span>
+	}
+}
+
+// SidebarNavItemRow renders one nav list item.
+// If item.Href is empty, renders as a non-interactive div (visual-only, per D-N02).
+// If item.Href is non-empty, renders as an anchor tag.
+templ SidebarNavItemRow(item sidebarNavItem) {
+	if item.Href == "" {
+		<div class={ sidebarNavItemClass(item.Active) } style="cursor: default">
+			<div class="sidebar-nav-link-inner">
+				<span class="sidebar-nav-icon">
+					@SidebarNavIcon(item.Icon)
+				</span>
+				<div class="sidebar-nav-label">{ item.Label }</div>
+			</div>
+		</div>
+	} else {
+		<a href={ templ.SafeURL(item.Href) } class={ sidebarNavItemClass(item.Active) }>
+			<div class="sidebar-nav-link-inner">
+				<span class="sidebar-nav-icon">
+					@SidebarNavIcon(item.Icon)
+				</span>
+				<div class="sidebar-nav-label">{ item.Label }</div>
+			</div>
+		</a>
+	}
+}
+
+// SidebarProjectsSection renders the projects list in the sidebar.
+templ SidebarProjectsSection(tablos []sqlc.Tablo) {
+	<div class="sidebar-projects">
+		<hr role="separator"/>
+		<div class="sidebar-section-label">Projects</div>
+		<ul class="sidebar-project-list">
+			for _, tablo := range tablos {
+				<li>
+					<a href={ templ.SafeURL("/tablos/" + tablo.ID.String()) } class="sidebar-project-link">
+						if tablo.Color.Valid && tablo.Color.String != "" {
+							<span class="sidebar-project-icon" style={ "background-color: " + tablo.Color.String }></span>
+						} else {
+							<span class="sidebar-project-icon"></span>
+						}
+						<span class="sidebar-project-label">{ tablo.Title }</span>
+					</a>
+				</li>
+			}
+		</ul>
+	</div>
+}
+
+// SidebarOrganizationFooter renders the user/org info at the bottom of the sidebar.
+// Per D-F01/D-F02/D-F03: shows user email initial as avatar, email as name, and logout form.
+templ SidebarOrganizationFooter(user *auth.User, csrfToken string) {
+	<div class="sidebar-organization">
+		<div class="organization-button">
+			<span class="organization-avatar">{ string([]rune(user.Email)[:1]) }</span>
+			<span class="organization-copy">
+				<span class="organization-name">{ user.Email }</span>
+			</span>
+		</div>
+		<form method="POST" action="/logout">
+			@ui.CSRFField(csrfToken)
+			<button type="submit" class="text-sm">Log out</button>
+		</form>
+	</div>
+}
+
+// DashboardSidebar renders the full sidebar with brand, nav, projects, and footer.
+templ DashboardSidebar(activePath string, tablos []sqlc.Tablo, user *auth.User, csrfToken string) {
+	<aside class="dashboard-sidebar">
+		<nav aria-label="Main navigation" class="sidebar-nav-shell">
+			<div class="sidebar-brand">
+				<a class="sidebar-brand-link" href="/" aria-label="Home">
+					<img class="sidebar-brand-logo" src="/static/logo_dark.png" alt="Logo XTablo"/>
+					<h1 class="sidebar-brand-title">XTablo</h1>
+				</a>
+			</div>
+			<div class="sidebar-primary">
+				<ul class="sidebar-list" role="list">
+					for _, item := range sidebarPrimaryNavItems(activePath) {
+						<li>
+							@SidebarNavItemRow(item)
+						</li>
+						if item.DividerAfter {
+							<li class="sidebar-divider"><hr role="separator"/></li>
+						}
+					}
+				</ul>
+				@SidebarProjectsSection(tablos)
+				@SidebarOrganizationFooter(user, csrfToken)
+			</div>
+		</nav>
+	</aside>
+}
+
+// AppLayout is the authenticated HTML shell for all dashboard pages.
+// It replaces Layout for all authenticated routes in Phase 15+.
+//
+// Differences from Layout:
+//   - Uses .dashboard-shell grid with sidebar + main content
+//   - DashboardSidebar renders nav, projects, and org footer
+//   - main#app-main-content.dashboard-main wraps page children
+//   - Scripts: htmx.min.js, sortable.min.js, discussion-sse.js (per D-L04)
+templ AppLayout(title string, user *auth.User, csrfToken string, activePath string, tablos []sqlc.Tablo) {
+	<!DOCTYPE html>
+	<html lang="en">
+		<head>
+			<meta charset="utf-8"/>
+			<meta name="viewport" content="width=device-width, initial-scale=1"/>
+			<title>{ title }</title>
+			<link rel="stylesheet" href="/static/tailwind.css"/>
+		</head>
+		<body>
+			<div class="dashboard-shell">
+				@DashboardSidebar(activePath, tablos, user, csrfToken)
+				<main id="app-main-content" class="dashboard-main">
+					{ children... }
+				</main>
+			</div>
+			<script src="/static/htmx.min.js" defer></script>
+			<script src="/static/sortable.min.js" defer></script>
+			<script src="/static/discussion-sse.js" defer></script>
+		</body>
+	</html>
+}

backend/templates/app_layout_helpers.go

@@ -0,0 +1,55 @@
+package templates
+
+import "strings"
+
+// sidebarNavItem describes one entry in the sidebar primary navigation list.
+type sidebarNavItem struct {
+	Href         string
+	Label        string
+	Icon         string
+	Active       bool
+	DividerAfter bool
+}
+
+// sidebarNavItemClass returns the CSS class string for a nav item.
+// Active items receive "sidebar-nav-item is-active"; inactive receive "sidebar-nav-item".
+func sidebarNavItemClass(active bool) string {
+	if active {
+		return "sidebar-nav-item is-active"
+	}
+	return "sidebar-nav-item"
+}
+
+// isActivePath reports whether activePath matches href.
+// Returns false when activePath is empty or blank.
+func isActivePath(activePath string, href string) bool {
+	return strings.TrimSpace(activePath) != "" && activePath == href
+}
+
+// sidebarNavItemID returns a stable HTML id attribute for the given nav href.
+func sidebarNavItemID(href string) string {
+	switch href {
+	case "/":
+		return "sidebar-nav-home"
+	default:
+		slug := strings.Trim(strings.ReplaceAll(href, "/", "-"), "-")
+		if slug == "" {
+			slug = "item"
+		}
+		return "sidebar-nav-" + slug
+	}
+}
+
+// sidebarPrimaryNavItems returns the ordered list of primary nav items with
+// active state computed from activePath.
+//
+// Per D-N01/D-N02: Tasks, Chat, and Files are visual-only (no Href) in Phase 15.
+func sidebarPrimaryNavItems(activePath string) []sidebarNavItem {
+	return []sidebarNavItem{
+		{Href: "/", Label: "Dashboard", Icon: "panels", Active: isActivePath(activePath, "/"), DividerAfter: true},
+		{Href: "", Label: "Tasks", Icon: "tasks", Active: false},
+		{Href: "/planning", Label: "Planning", Icon: "planning", Active: isActivePath(activePath, "/planning")},
+		{Href: "", Label: "Chat", Icon: "chat", Active: false},
+		{Href: "", Label: "Files", Icon: "files", Active: false},
+	}
+}