Add internal provision endpoint for rSpace Registry

Auth-free POST /api/internal/provision creates default Notebook + system User
+ OWNER collaborator scoped to workspace slug.

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

src/app/api/internal/provision/route.ts

@@ -0,0 +1,46 @@
+import { NextResponse } from "next/server";
+import { prisma } from "@/lib/prisma";
+
+/**
+ * Internal provision endpoint — called by rSpace Registry when activating
+ * this app for a space. No auth required (only reachable from Docker network).
+ *
+ * Creates a default Notebook scoped to the workspace slug + a system collaborator.
+ */
+export async function POST(request: Request) {
+  const body = await request.json();
+  const space: string = body.space?.trim();
+  if (!space) {
+    return NextResponse.json({ error: "Missing space name" }, { status: 400 });
+  }
+
+  // Check if a notebook already exists for this workspace
+  const existing = await prisma.notebook.findFirst({
+    where: { workspaceSlug: space },
+  });
+  if (existing) {
+    return NextResponse.json({ status: "exists", id: existing.id, slug: existing.slug });
+  }
+
+  const systemDid = `did:system:${space}`;
+  const user = await prisma.user.upsert({
+    where: { did: systemDid },
+    update: {},
+    create: { did: systemDid, username: `${space}-admin` },
+  });
+
+  const notebook = await prisma.notebook.create({
+    data: {
+      title: `${space.charAt(0).toUpperCase() + space.slice(1)} Notes`,
+      slug: `${space}-notes`,
+      description: body.description || `Shared notes for ${space}`,
+      workspaceSlug: space,
+      isPublic: body.public ?? false,
+      collaborators: {
+        create: { userId: user.id, role: "OWNER" },
+      },
+    },
+  });
+
+  return NextResponse.json({ status: "created", id: notebook.id, slug: notebook.slug }, { status: 201 });
+}