refactor(errors): migrate decisions to {code,msg}

lib/decision.ts

@@ -0,0 +1,18 @@
+import type { Actor } from "@/lib/actor"
+import type { ApiDecision } from "@/lib/errors"
+
+export function allow(): ApiDecision {
+  return { ok: true }
+}
+
+export function deny(code: number, msg: string): ApiDecision {
+  return { ok: false, error: { code, msg } }
+}
+
+export function requireAuth(actor: Actor | null | undefined): ApiDecision {
+  if (!actor?.userId) {
+    return deny(401, "请先登录")
+  }
+
+  return allow()
+}