Add internal provision endpoint for rSpace Registry

Simple acknowledge endpoint — calendars associated in future.

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

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

@@ -0,0 +1,17 @@
+import { NextResponse } from "next/server";
+
+/**
+ * Internal provision endpoint — called by rSpace Registry when activating
+ * this app for a space. No auth required (only reachable from Docker network).
+ *
+ * rcal will associate calendars with space slugs in future.
+ * Acknowledges provisioning for now.
+ */
+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 });
+  }
+  return NextResponse.json({ status: "ok", space, message: "rcal space acknowledged" });
+}