test(channelserver): add store tests and document lock ordering

Add unit tests with race-detector coverage for QuestCache,
UserBinaryStore, and MinidataStore (18 tests covering hits, misses,
expiry, copy isolation, and concurrent access).

Document the lock acquisition order on the Server struct to prevent
future deadlocks: Server.Mutex → stagesLock → Stage → semaphoreLock.

server/channelserver/user_binary_store_test.go

@@ -0,0 +1,103 @@
+package channelserver
+
+import (
+	"sync"
+	"testing"
+)
+
+func TestUserBinaryStore_GetMiss(t *testing.T) {
+	s := NewUserBinaryStore()
+	_, ok := s.Get(1, 1)
+	if ok {
+		t.Error("expected miss for unknown key")
+	}
+}
+
+func TestUserBinaryStore_SetGet(t *testing.T) {
+	s := NewUserBinaryStore()
+	data := []byte{0x01, 0x02, 0x03}
+	s.Set(100, 3, data)
+
+	got, ok := s.Get(100, 3)
+	if !ok {
+		t.Fatal("expected hit")
+	}
+	if len(got) != 3 || got[0] != 0x01 {
+		t.Errorf("got %v, want [1 2 3]", got)
+	}
+}
+
+func TestUserBinaryStore_DifferentIndexes(t *testing.T) {
+	s := NewUserBinaryStore()
+	s.Set(1, 1, []byte{0xAA})
+	s.Set(1, 2, []byte{0xBB})
+
+	got1, _ := s.Get(1, 1)
+	got2, _ := s.Get(1, 2)
+	if got1[0] != 0xAA || got2[0] != 0xBB {
+		t.Error("different indexes should store independent data")
+	}
+}
+
+func TestUserBinaryStore_Delete(t *testing.T) {
+	s := NewUserBinaryStore()
+	s.Set(1, 3, []byte{0x01})
+	s.Delete(1, 3)
+
+	_, ok := s.Get(1, 3)
+	if ok {
+		t.Error("expected miss after delete")
+	}
+}
+
+func TestUserBinaryStore_DeleteNonExistent(t *testing.T) {
+	s := NewUserBinaryStore()
+	s.Delete(999, 1) // should not panic
+}
+
+func TestUserBinaryStore_GetCopy(t *testing.T) {
+	s := NewUserBinaryStore()
+	s.Set(1, 3, []byte{0x01, 0x02})
+
+	cp := s.GetCopy(1, 3)
+	if cp[0] != 0x01 || cp[1] != 0x02 {
+		t.Fatal("copy data mismatch")
+	}
+
+	// Mutating the copy must not affect the store
+	cp[0] = 0xFF
+	orig, _ := s.Get(1, 3)
+	if orig[0] == 0xFF {
+		t.Error("GetCopy returned a reference, not a copy")
+	}
+}
+
+func TestUserBinaryStore_GetCopyMiss(t *testing.T) {
+	s := NewUserBinaryStore()
+	cp := s.GetCopy(999, 1)
+	if cp != nil {
+		t.Error("expected nil for missing key")
+	}
+}
+
+func TestUserBinaryStore_ConcurrentAccess(t *testing.T) {
+	s := NewUserBinaryStore()
+	var wg sync.WaitGroup
+	for i := uint32(0); i < 100; i++ {
+		wg.Add(3)
+		charID := i
+		go func() {
+			defer wg.Done()
+			s.Set(charID, 1, []byte{byte(charID)})
+		}()
+		go func() {
+			defer wg.Done()
+			s.Get(charID, 1)
+		}()
+		go func() {
+			defer wg.Done()
+			s.GetCopy(charID, 1)
+		}()
+	}
+	wg.Wait()
+}