ui: shadcn-ui + React island shells for pages, Redis session store

Rewrite the dashboard, machines, users, dns, and settings pages as thin
Astro shells that mount a matching React island (Dashboard, MachinesPage,
UsersPage, DnsPage, SettingsPage) built on the shadcn-ui component
library. Alpine.js templates in those pages are replaced wholesale;
Alpine still ships as the runtime for the ACL editor's dependencies.

- src/components/ui/*: shadcn primitives (button, card, tabs, select,
  dropdown-menu, avatar, badge, input, switch, separator)
- src/components/{dashboard,dns,machines,settings,users}/*: page-level
  React shells that consume server props from the Astro parent
- src/components/shell/AppShell.tsx: shared chrome (nav, user menu)
- src/lib/utils.ts: shadcn's cn() helper
- src/lib/auth/session-manager.ts: pluggable SessionStore interface with
  Redis (via REDIS_URL) or in-memory backends; both honor absolute
  expiration via TTL. In-memory logs a warning that sessions vanish on
  restart.
- src/lib/auth/oidc-client.ts, oidc-state.ts: shrink OIDC handlers now
  that PKCE + nonce state travels in a signed JWT cookie
- src/pages/api/auth/*: match the simplified handlers
- src/styles/global.css, tailwind.config.mjs, tsconfig.json: shadcn
  design tokens and the '@/*' path alias
- docker-compose.local.yml: local dev tweaks
- package.json, pnpm-lock.yaml: shadcn + Radix + ioredis + zod

src/components/ui/dropdown-menu.tsx

@@ -0,0 +1,143 @@
+import * as DropdownMenuPrimitive from '@radix-ui/react-dropdown-menu';
+import { Check, ChevronRight, Circle } from 'lucide-react';
+import * as React from 'react';
+import { cn } from '@/lib/utils';
+
+const DropdownMenu = DropdownMenuPrimitive.Root;
+const DropdownMenuTrigger = DropdownMenuPrimitive.Trigger;
+const DropdownMenuGroup = DropdownMenuPrimitive.Group;
+const DropdownMenuPortal = DropdownMenuPrimitive.Portal;
+const DropdownMenuSub = DropdownMenuPrimitive.Sub;
+const DropdownMenuRadioGroup = DropdownMenuPrimitive.RadioGroup;
+
+const DropdownMenuSubTrigger = React.forwardRef<
+	React.ElementRef<typeof DropdownMenuPrimitive.SubTrigger>,
+	React.ComponentPropsWithoutRef<typeof DropdownMenuPrimitive.SubTrigger> & {
+		inset?: boolean;
+	}
+>(({ className, inset, children, ...props }, ref) => (
+	<DropdownMenuPrimitive.SubTrigger
+		ref={ref}
+		className={cn(
+			'flex cursor-default select-none items-center gap-2 rounded-sm px-2 py-1.5 text-sm outline-none focus:bg-accent data-[state=open]:bg-accent [&_svg]:pointer-events-none [&_svg]:size-4 [&_svg]:shrink-0',
+			inset && 'pl-8',
+			className,
+		)}
+		{...props}
+	>
+		{children}
+		<ChevronRight className="ml-auto" />
+	</DropdownMenuPrimitive.SubTrigger>
+));
+DropdownMenuSubTrigger.displayName =
+	DropdownMenuPrimitive.SubTrigger.displayName;
+
+const DropdownMenuSubContent = React.forwardRef<
+	React.ElementRef<typeof DropdownMenuPrimitive.SubContent>,
+	React.ComponentPropsWithoutRef<typeof DropdownMenuPrimitive.SubContent>
+>(({ className, ...props }, ref) => (
+	<DropdownMenuPrimitive.SubContent
+		ref={ref}
+		className={cn(
+			'z-50 min-w-[8rem] overflow-hidden rounded-md border bg-popover p-1 text-popover-foreground shadow-lg data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0 data-[state=closed]:zoom-out-95 data-[state=open]:zoom-in-95 data-[side=bottom]:slide-in-from-top-2 data-[side=left]:slide-in-from-right-2 data-[side=right]:slide-in-from-left-2 data-[side=top]:slide-in-from-bottom-2',
+			className,
+		)}
+		{...props}
+	/>
+));
+DropdownMenuSubContent.displayName =
+	DropdownMenuPrimitive.SubContent.displayName;
+
+const DropdownMenuContent = React.forwardRef<
+	React.ElementRef<typeof DropdownMenuPrimitive.Content>,
+	React.ComponentPropsWithoutRef<typeof DropdownMenuPrimitive.Content>
+>(({ className, sideOffset = 4, ...props }, ref) => (
+	<DropdownMenuPrimitive.Portal>
+		<DropdownMenuPrimitive.Content
+			ref={ref}
+			sideOffset={sideOffset}
+			className={cn(
+				'z-50 min-w-[8rem] overflow-hidden rounded-md border bg-popover p-1 text-popover-foreground shadow-md data-[state=open]:animate-in data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=open]:fade-in-0 data-[state=closed]:zoom-out-95 data-[state=open]:zoom-in-95 data-[side=bottom]:slide-in-from-top-2 data-[side=left]:slide-in-from-right-2 data-[side=right]:slide-in-from-left-2 data-[side=top]:slide-in-from-bottom-2',
+				className,
+			)}
+			{...props}
+		/>
+	</DropdownMenuPrimitive.Portal>
+));
+DropdownMenuContent.displayName = DropdownMenuPrimitive.Content.displayName;
+
+const DropdownMenuItem = React.forwardRef<
+	React.ElementRef<typeof DropdownMenuPrimitive.Item>,
+	React.ComponentPropsWithoutRef<typeof DropdownMenuPrimitive.Item> & {
+		inset?: boolean;
+	}
+>(({ className, inset, ...props }, ref) => (
+	<DropdownMenuPrimitive.Item
+		ref={ref}
+		className={cn(
+			"relative flex cursor-default select-none items-center gap-2 rounded-sm px-2 py-1.5 text-sm outline-none transition-colors focus:bg-accent focus:text-accent-foreground data-[disabled]:pointer-events-none data-[disabled]:opacity-50 [&>svg]:size-4 [&>svg]:shrink-0",
+			inset && 'pl-8',
+			className,
+		)}
+		{...props}
+	/>
+));
+DropdownMenuItem.displayName = DropdownMenuPrimitive.Item.displayName;
+
+const DropdownMenuLabel = React.forwardRef<
+	React.ElementRef<typeof DropdownMenuPrimitive.Label>,
+	React.ComponentPropsWithoutRef<typeof DropdownMenuPrimitive.Label> & {
+		inset?: boolean;
+	}
+>(({ className, inset, ...props }, ref) => (
+	<DropdownMenuPrimitive.Label
+		ref={ref}
+		className={cn(
+			'px-2 py-1.5 text-sm font-semibold',
+			inset && 'pl-8',
+			className,
+		)}
+		{...props}
+	/>
+));
+DropdownMenuLabel.displayName = DropdownMenuPrimitive.Label.displayName;
+
+const DropdownMenuSeparator = React.forwardRef<
+	React.ElementRef<typeof DropdownMenuPrimitive.Separator>,
+	React.ComponentPropsWithoutRef<typeof DropdownMenuPrimitive.Separator>
+>(({ className, ...props }, ref) => (
+	<DropdownMenuPrimitive.Separator
+		ref={ref}
+		className={cn('-mx-1 my-1 h-px bg-muted', className)}
+		{...props}
+	/>
+));
+DropdownMenuSeparator.displayName =
+	DropdownMenuPrimitive.Separator.displayName;
+
+const DropdownMenuShortcut = ({
+	className,
+	...props
+}: React.HTMLAttributes<HTMLSpanElement>) => (
+	<span
+		className={cn('ml-auto text-xs tracking-widest opacity-60', className)}
+		{...props}
+	/>
+);
+DropdownMenuShortcut.displayName = 'DropdownMenuShortcut';
+
+export {
+	DropdownMenu,
+	DropdownMenuTrigger,
+	DropdownMenuContent,
+	DropdownMenuItem,
+	DropdownMenuLabel,
+	DropdownMenuSeparator,
+	DropdownMenuShortcut,
+	DropdownMenuGroup,
+	DropdownMenuPortal,
+	DropdownMenuSub,
+	DropdownMenuSubContent,
+	DropdownMenuSubTrigger,
+	DropdownMenuRadioGroup,
+};