avoid stderr output in zig build test/move test to Lru

src/cache/Cache.zig

@@ -275,33 +275,3 @@ test "L1/L2 cache flow" {
     // Now it should be in L1
     try std.testing.expectEqualStrings("value1", cache.lru.get("key1").?);
 }
-
-test "expired cache entry returns null" {
-    const allocator = std.testing.allocator;
-
-    var tmp_dir = std.testing.tmpDir(.{});
-    defer tmp_dir.cleanup();
-
-    var path_buf: [std.fs.max_path_bytes]u8 = undefined;
-    const cache_dir = try tmp_dir.dir.realpath(".", &path_buf);
-
-    const cache = try Cache.init(allocator, .{ .max_entries = 10, .cache_dir = cache_dir });
-    defer cache.deinit();
-
-    // Put item with past expiration time
-    const now = std.time.milliTimestamp();
-    const past_expires = now - 1000;
-
-    // Manually insert expired entry into L1
-    const key_copy = try allocator.dupe(u8, "key1");
-    const value_copy = try allocator.dupe(u8, "value1");
-    try cache.lru.map.put(key_copy, .{
-        .value = value_copy,
-        .expires = past_expires,
-        .access_count = 0,
-    });
-
-    // Get should return null for expired entry
-    const result = cache.get("key1");
-    try std.testing.expect(result == null);
-}

src/cache/Lru.zig

@@ -137,3 +137,18 @@ test "LRU eviction" {
 
     try std.testing.expect(lru.get("key1") == null);
 }
+
+test "LRU expired entry returns null" {
+    var lru = try Lru.init(std.testing.allocator, 10);
+    defer lru.deinit();
+
+    // Put item with past expiration time
+    const now = std.time.milliTimestamp();
+    const past_expires = now - 1000;
+
+    try lru.put("key1", "value1", past_expires);
+
+    // Get should return null for expired entry
+    const result = lru.get("key1");
+    try std.testing.expect(result == null);
+}