feat(protbot): add headless MHF protocol bot as cmd/protbot

Copy MHBridge into the Erupe module as cmd/protbot/ so it can be
built, tested, and maintained alongside the server. The bot
implements the full sign → entrance → channel login flow and
supports lobby entry, chat, session setup, and quest enumeration.

The conn/ package keeps its own Blowfish crypto primitives to avoid
importing erupe-ce/config (which requires a config file at init).

cmd/protbot/scenario/quest.go

@@ -0,0 +1,31 @@
+package scenario
+
+import (
+	"fmt"
+	"time"
+
+	"erupe-ce/cmd/protbot/protocol"
+)
+
+// EnumerateQuests sends MSG_MHF_ENUMERATE_QUEST and returns the raw quest list data.
+func EnumerateQuests(ch *protocol.ChannelConn, world uint8, counter uint16) ([]byte, error) {
+	ack := ch.NextAckHandle()
+	pkt := protocol.BuildEnumerateQuestPacket(ack, world, counter, 0)
+	fmt.Printf("[quest] Sending MSG_MHF_ENUMERATE_QUEST (world=%d, counter=%d, ackHandle=%d)...\n",
+		world, counter, ack)
+	if err := ch.SendPacket(pkt); err != nil {
+		return nil, fmt.Errorf("enumerate quest send: %w", err)
+	}
+
+	resp, err := ch.WaitForAck(ack, 15*time.Second)
+	if err != nil {
+		return nil, fmt.Errorf("enumerate quest ack: %w", err)
+	}
+	if resp.ErrorCode != 0 {
+		return nil, fmt.Errorf("enumerate quest failed: error code %d", resp.ErrorCode)
+	}
+	fmt.Printf("[quest] ENUMERATE_QUEST ACK (error=%d, %d bytes data)\n",
+		resp.ErrorCode, len(resp.Data))
+
+	return resp.Data, nil
+}