feat(webhooks): outbound webhooks with HMAC-SHA256 signing and API key auth

Webhook registration/management. HMAC-signed delivery with retry.
Events: recipe.created/updated, comment.created, follower.new.
REST API key creation for programmatic access.

apps/web/app/api/v1/webhooks/[id]/deliveries/route.ts

@@ -0,0 +1,27 @@
+import { NextRequest, NextResponse } from "next/server";
+import { db, webhooks, webhookDeliveries, eq, and, desc } from "@epicure/db";
+import { requireSession } from "@/lib/api-auth";
+
+type Params = { params: Promise<{ id: string }> };
+
+export async function GET(_req: NextRequest, { params }: Params) {
+  const { session, response } = await requireSession();
+  if (response) return response;
+
+  const { id } = await params;
+
+  const hook = await db.query.webhooks.findFirst({
+    where: and(eq(webhooks.id, id), eq(webhooks.userId, session!.user.id)),
+    columns: { id: true },
+  });
+  if (!hook) return NextResponse.json({ error: "Not found" }, { status: 404 });
+
+  const deliveries = await db
+    .select()
+    .from(webhookDeliveries)
+    .where(eq(webhookDeliveries.webhookId, id))
+    .orderBy(desc(webhookDeliveries.createdAt))
+    .limit(20);
+
+  return NextResponse.json(deliveries);
+}