test: use callable assert() so TS narrows moe

`assert.ok(x, msg)` doesn't carry an `asserts value` signature, so the
CI build flagged `moe` as possibly undefined on the lines below. Use
the plain callable form, matching the existing `assert(!parse.sharded)`
pattern in this file.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: mishig25

packages/hub/src/lib/parse-safetensors-metadata.spec.ts

@@ -159,7 +159,7 @@ describe("parseSafetensorsMetadata", () => {
 		});
 
 		assert(parse.sharded);
-		assert.ok(parse.moe, "expected `moe` field on MoE repo");
+		assert(parse.moe, "expected `moe` field on MoE repo");
 		assert.strictEqual(parse.moe.numExperts, 8);
 		assert.strictEqual(parse.moe.topK, 2);
 		assert.strictEqual(parse.moe.hasSharedExpert, false);
@@ -176,7 +176,7 @@ describe("parseSafetensorsMetadata", () => {
 		});
 
 		assert(parse.sharded);
-		assert.ok(parse.moe, "expected `moe` field on MoE repo");
+		assert(parse.moe, "expected `moe` field on MoE repo");
 		assert.strictEqual(parse.moe.numExperts, 128);
 		assert.strictEqual(parse.moe.topK, 8);
 		// Published: A3B (3B active).
@@ -191,7 +191,7 @@ describe("parseSafetensorsMetadata", () => {
 		});
 
 		assert(parse.sharded);
-		assert.ok(parse.moe, "expected `moe` field on MoE repo");
+		assert(parse.moe, "expected `moe` field on MoE repo");
 		assert.strictEqual(parse.moe.numExperts, 64);
 		assert.strictEqual(parse.moe.topK, 6);
 		assert.strictEqual(parse.moe.hasSharedExpert, true);