refactor(channelserver): consolidate tests into matching source test files

Move ~300 test functions from 21 catch-all files (handlers_core_test.go,
handlers_coverage*_test.go, *_coverage_test.go) into the *_test.go file
matching each handler's source file. This makes tests discoverable by
convention: tests for handlers_guild.go live in handlers_guild_test.go.

New files: handlers_guild_mission_test.go, sys_time_test.go.
No test logic changed — pure file reorganization.

server/channelserver/handlers_reward_test.go

@@ -124,3 +124,92 @@ func TestHandleMsgMhfAcceptReadReward(t *testing.T) {
 
 	handleMsgMhfAcceptReadReward(session, nil)
 }
+
+// Tests consolidated from handlers_coverage3_test.go
+
+func TestSimpleAckHandlers_RewardGo(t *testing.T) {
+	server := createMockServer()
+
+	tests := []struct {
+		name string
+		fn   func(s *Session)
+	}{
+		{"handleMsgMhfGetRewardSong", func(s *Session) {
+			handleMsgMhfGetRewardSong(s, &mhfpacket.MsgMhfGetRewardSong{AckHandle: 1})
+		}},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			session := createMockSession(1, server)
+			tt.fn(session)
+			select {
+			case p := <-session.sendPackets:
+				if len(p.data) == 0 {
+					t.Errorf("%s: response should have data", tt.name)
+				}
+			default:
+				t.Errorf("%s: no response queued", tt.name)
+			}
+		})
+	}
+}
+
+func TestNonTrivialHandlers_RewardGo(t *testing.T) {
+	server := createMockServer()
+
+	tests := []struct {
+		name string
+		fn   func(s *Session)
+	}{
+		{"handleMsgMhfGetAdditionalBeatReward", func(s *Session) {
+			handleMsgMhfGetAdditionalBeatReward(s, &mhfpacket.MsgMhfGetAdditionalBeatReward{AckHandle: 1})
+		}},
+		{"handleMsgMhfGetUdRankingRewardList", func(s *Session) {
+			handleMsgMhfGetUdRankingRewardList(s, &mhfpacket.MsgMhfGetUdRankingRewardList{AckHandle: 1})
+		}},
+		{"handleMsgMhfAcquireMonthlyReward", func(s *Session) {
+			handleMsgMhfAcquireMonthlyReward(s, &mhfpacket.MsgMhfAcquireMonthlyReward{AckHandle: 1})
+		}},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			session := createMockSession(1, server)
+			tt.fn(session)
+			select {
+			case p := <-session.sendPackets:
+				if len(p.data) == 0 {
+					t.Errorf("%s: response should have data", tt.name)
+				}
+			default:
+				t.Errorf("%s: no response queued", tt.name)
+			}
+		})
+	}
+}
+
+func TestEmptyHandlers_MiscFiles_Reward(t *testing.T) {
+	server := createMockServer()
+	session := createMockSession(1, server)
+
+	tests := []struct {
+		name string
+		fn   func()
+	}{
+		{"handleMsgMhfUseRewardSong", func() { handleMsgMhfUseRewardSong(session, nil) }},
+		{"handleMsgMhfAddRewardSongCount", func() { handleMsgMhfAddRewardSongCount(session, nil) }},
+		{"handleMsgMhfAcceptReadReward", func() { handleMsgMhfAcceptReadReward(session, nil) }},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			defer func() {
+				if r := recover(); r != nil {
+					t.Errorf("%s panicked: %v", tt.name, r)
+				}
+			}()
+			tt.fn()
+		})
+	}
+}