test: increase total coverage from 46.1% to 50.5%

- Fix duplicate test declarations across coverage2, misc, mercenary, event files
- Fix signserver TestHandlePacketDELETE timeout (multi-write pipe deadlock)
- Fix entranceserver build error (invalid -1 for uint16 port)
- Add handlers_reserve_test.go covering all 56 reserve handler stubs
- Add handlers_coverage3_test.go with 115+ handler tests
- Add handlers_register_test.go with 55 Raviente register/load tests
- Add handlers_coverage_test.go, signserver, entranceserver, usercheck tests

server/channelserver/handlers_coverage_test.go

@@ -0,0 +1,145 @@
+package channelserver
+
+import (
+	"testing"
+
+	"erupe-ce/network/mhfpacket"
+)
+
+// Tests for handlers that do NOT require database access, exercising additional
+// code paths not covered by existing test files (handlers_core_test.go,
+// handlers_rengoku_test.go, etc.).
+
+// TestHandleMsgSysPing_DifferentAckHandles verifies ping works with various ack handles.
+func TestHandleMsgSysPing_DifferentAckHandles(t *testing.T) {
+	server := createMockServer()
+
+	ackHandles := []uint32{0, 1, 99999, 0xFFFFFFFF}
+	for _, ack := range ackHandles {
+		session := createMockSession(1, server)
+		pkt := &mhfpacket.MsgSysPing{AckHandle: ack}
+
+		handleMsgSysPing(session, pkt)
+
+		select {
+		case p := <-session.sendPackets:
+			if len(p.data) == 0 {
+				t.Errorf("AckHandle=%d: Response packet should have data", ack)
+			}
+		default:
+			t.Errorf("AckHandle=%d: No response packet queued", ack)
+		}
+	}
+}
+
+// TestHandleMsgSysTerminalLog_NoEntries verifies the handler works with nil entries.
+func TestHandleMsgSysTerminalLog_NoEntries(t *testing.T) {
+	server := createMockServer()
+	session := createMockSession(1, server)
+
+	pkt := &mhfpacket.MsgSysTerminalLog{
+		AckHandle: 99999,
+		LogID:     0,
+		Entries:   nil,
+	}
+
+	handleMsgSysTerminalLog(session, pkt)
+
+	select {
+	case p := <-session.sendPackets:
+		if len(p.data) == 0 {
+			t.Error("Response packet should have data")
+		}
+	default:
+		t.Error("No response packet queued")
+	}
+}
+
+// TestHandleMsgSysTerminalLog_ManyEntries verifies the handler with many log entries.
+func TestHandleMsgSysTerminalLog_ManyEntries(t *testing.T) {
+	server := createMockServer()
+	session := createMockSession(1, server)
+
+	entries := make([]*mhfpacket.TerminalLogEntry, 20)
+	for i := range entries {
+		entries[i] = &mhfpacket.TerminalLogEntry{
+			Index: uint32(i),
+			Type1: uint8(i % 256),
+			Type2: uint8((i + 1) % 256),
+			Data:  make([]int16, 15),
+		}
+	}
+
+	pkt := &mhfpacket.MsgSysTerminalLog{
+		AckHandle: 55555,
+		LogID:     42,
+		Entries:   entries,
+	}
+
+	handleMsgSysTerminalLog(session, pkt)
+
+	select {
+	case p := <-session.sendPackets:
+		if len(p.data) == 0 {
+			t.Error("Response packet should have data")
+		}
+	default:
+		t.Error("No response packet queued")
+	}
+}
+
+// TestHandleMsgSysTime_MultipleCalls verifies calling time handler repeatedly.
+func TestHandleMsgSysTime_MultipleCalls(t *testing.T) {
+	server := createMockServer()
+	session := createMockSession(1, server)
+
+	pkt := &mhfpacket.MsgSysTime{
+		GetRemoteTime: false,
+		Timestamp:     0,
+	}
+
+	for i := 0; i < 5; i++ {
+		handleMsgSysTime(session, pkt)
+	}
+
+	// Should have 5 queued responses
+	count := 0
+	for {
+		select {
+		case p := <-session.sendPackets:
+			if len(p.data) == 0 {
+				t.Error("Response packet should have data")
+			}
+			count++
+		default:
+			goto done
+		}
+	}
+done:
+	if count != 5 {
+		t.Errorf("Expected 5 queued responses, got %d", count)
+	}
+}
+
+// TestHandleMsgMhfGetRengokuRankingRank_DifferentAck verifies rengoku ranking
+// works with different ack handles.
+func TestHandleMsgMhfGetRengokuRankingRank_DifferentAck(t *testing.T) {
+	server := createMockServer()
+
+	ackHandles := []uint32{0, 1, 54321, 0xDEADBEEF}
+	for _, ack := range ackHandles {
+		session := createMockSession(1, server)
+		pkt := &mhfpacket.MsgMhfGetRengokuRankingRank{AckHandle: ack}
+
+		handleMsgMhfGetRengokuRankingRank(session, pkt)
+
+		select {
+		case p := <-session.sendPackets:
+			if len(p.data) == 0 {
+				t.Errorf("AckHandle=%d: Response packet should have data", ack)
+			}
+		default:
+			t.Errorf("AckHandle=%d: No response packet queued", ack)
+		}
+	}
+}