feat: ST-001–ST-005 foundation — scaffolding, Prisma, schema, seed, env

- ST-001: Next.js 16 + React 19 + TypeScript strict + Tailwind + shadcn/ui + all deps
- ST-002: Prisma v7 setup with better-sqlite3 adapter (local) and pg adapter (cloud)
- ST-003: Full schema migration (users, pbis, stories, sprints, tasks, todos, api_tokens)
- ST-004: Seed with 9 PBIs, ~40 stories, demo user (demo/demo1234), lars user
- ST-005: Zod-validated env vars, .env.example, lib/session, lib/auth, lib/api-auth

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

components/ui/separator.tsx

@@ -0,0 +1,25 @@
+"use client"
+
+import { Separator as SeparatorPrimitive } from "@base-ui/react/separator"
+
+import { cn } from "@/lib/utils"
+
+function Separator({
+  className,
+  orientation = "horizontal",
+  ...props
+}: SeparatorPrimitive.Props) {
+  return (
+    <SeparatorPrimitive
+      data-slot="separator"
+      orientation={orientation}
+      className={cn(
+        "shrink-0 bg-border data-horizontal:h-px data-horizontal:w-full data-vertical:w-px data-vertical:self-stretch",
+        className
+      )}
+      {...props}
+    />
+  )
+}
+
+export { Separator }