refactor(web): split into GPL standalone editor + thin reference backend

Reduce web/ to a single generic editor app plus a minimal example backend,
moving all project-specific/app code out to the closed root repo:

- apps/frontend -> standalone (@pcbjam/standalone): the GPL editor. Strips the
  project-management UI (ProjectsPage/ProjectDetailPage/UploadDropzone and the
  write half of lib/api.ts). WasmTool now takes fetchBytes + assetBaseUrl as
  injected props (decoupled from the API client) so it can be driven by either
  a backend or a local folder. New HomePage (local-folder loader + backend
  project list) and read-only ProjectView. BroadcastChannel collab unchanged.
- backend (@pcbjam/backend-example): thin Fastify+ts-rest reference impl of the
  @pcbjam/shared contract — serves a single project off the local filesystem
  (PROJECT_DIR), no DB/auth/uploads.
- packages/contract -> web/pcbjam-shared (git submodule, MIT @pcbjam/shared).
- Remove apps/server, packages/storage, packages/contract, docker-compose
  (server + storage move to the closed root repo; preserved via subtree
  branches). Rewrite pnpm-workspace/turbo/.env for the frontend-only layout.
- Add tests/fixtures/demo so the editor + example backend run out of the box.

Standalone typechecks + builds; backend serves the contract end-to-end.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/standalone/src/components/ui/card.tsx

@@ -0,0 +1,82 @@
+import * as React from "react";
+import { cn } from "@/lib/utils";
+
+const Card = React.forwardRef<
+  HTMLDivElement,
+  React.HTMLAttributes<HTMLDivElement>
+>(({ className, ...props }, ref) => (
+  <div
+    ref={ref}
+    className={cn(
+      "rounded-lg border bg-card text-card-foreground shadow-sm",
+      className,
+    )}
+    {...props}
+  />
+));
+Card.displayName = "Card";
+
+const CardHeader = React.forwardRef<
+  HTMLDivElement,
+  React.HTMLAttributes<HTMLDivElement>
+>(({ className, ...props }, ref) => (
+  <div
+    ref={ref}
+    className={cn("flex flex-col space-y-1.5 p-6", className)}
+    {...props}
+  />
+));
+CardHeader.displayName = "CardHeader";
+
+const CardTitle = React.forwardRef<
+  HTMLDivElement,
+  React.HTMLAttributes<HTMLDivElement>
+>(({ className, ...props }, ref) => (
+  <div
+    ref={ref}
+    className={cn("font-semibold leading-none tracking-tight", className)}
+    {...props}
+  />
+));
+CardTitle.displayName = "CardTitle";
+
+const CardDescription = React.forwardRef<
+  HTMLDivElement,
+  React.HTMLAttributes<HTMLDivElement>
+>(({ className, ...props }, ref) => (
+  <div
+    ref={ref}
+    className={cn("text-sm text-muted-foreground", className)}
+    {...props}
+  />
+));
+CardDescription.displayName = "CardDescription";
+
+const CardContent = React.forwardRef<
+  HTMLDivElement,
+  React.HTMLAttributes<HTMLDivElement>
+>(({ className, ...props }, ref) => (
+  <div ref={ref} className={cn("p-6 pt-0", className)} {...props} />
+));
+CardContent.displayName = "CardContent";
+
+const CardFooter = React.forwardRef<
+  HTMLDivElement,
+  React.HTMLAttributes<HTMLDivElement>
+>(({ className, ...props }, ref) => (
+  <div
+    ref={ref}
+    className={cn("flex items-center p-6 pt-0", className)}
+    {...props}
+  />
+));
+CardFooter.displayName = "CardFooter";
+
+export {
+  Card,
+  CardHeader,
+  CardFooter,
+  CardTitle,
+  CardDescription,
+  CardContent,
+};