feat(security): add CSRF protection for all state-changing API routes

- Synchronizer token stored in session; GET /auth/csrf to obtain it
- csrfProtection middleware requires X-CSRF-Token on non-safe methods
- customFetch injects the header via setCsrfTokenGetter
- toolrate boot loads token; reload after local login (session regenerate)
- OpenAPI GET /auth/csrf + CsrfToken schema, orval regenerated

artifacts/toolrate/src/lib/csrf.ts

@@ -0,0 +1,27 @@
+import { setCsrfTokenGetter } from "@workspace/api-client-react";
+
+let token: string | null = null;
+
+setCsrfTokenGetter(() => token);
+
+export function getCsrfToken(): string | null {
+  return token;
+}
+
+export async function loadCsrfToken(): Promise<string | null> {
+  try {
+    const res = await fetch(`/api/auth/csrf`, {
+      credentials: "include",
+    });
+    if (!res.ok) {
+      token = null;
+      return null;
+    }
+    const data = (await res.json()) as { token?: string };
+    token = data.token ?? null;
+    return token;
+  } catch {
+    token = null;
+    return null;
+  }
+}