feat(campaign): implement Event Tent campaign system

Adds the full campaign/event-tent feature:

Packet layer:
- MsgMhfApplyCampaign: Unk0/Unk1/Unk2 → CampaignID/Code (null-terminated 16-byte string)
- MsgMhfAcquireItem: Unk0/Length/Unk1 → RewardIDs []uint32
- MsgMhfEnumerateItem: remove Unk0/Unk1 (RE'd: zeroed + always-2, ignored)
- MsgMhfStateCampaign: Unk1 → NullPadding (RE'd: always zero)
- MsgMhfTransferItem: Unk0/Unk1/Unk2 → QuestID/ItemType/Quantity (RE'd)

Handler layer (handlers_campaign.go):
- handleMsgMhfEnumerateCampaign: reads campaigns, categories, links from DB;
  prefix moved into pascal string slot 3 of each event entry (RE confirmed
  3-section response format — removes spurious intermediate section)
- handleMsgMhfStateCampaign: returns stamp count and redeemable flag
- handleMsgMhfApplyCampaign: validates and records code redemption
- handleMsgMhfEnumerateItem: lists rewards gated by stamp count
- handleMsgMhfAcquireItem: marks rewards as claimed
- handleMsgMhfTransferItem: records campaign quest completion (item_type=9)

Quest gating (handlers_quest.go):
- makeEventQuest: for QuestTypeSpecialTool, check campaign stamp count and
  deadline before allowing the quest (WriteBool true/false)

Database:
- 0010_campaign.sql: 8-table schema (campaigns, categories, links, rewards,
  claimed, state, codes, quest)
- CampaignDemo.sql: community-researched live game campaign data

network/mhfpacket/msg_mhf_enumerate_item.go

@@ -11,8 +11,6 @@ import (
 // MsgMhfEnumerateItem represents the MSG_MHF_ENUMERATE_ITEM
 type MsgMhfEnumerateItem struct {
 	AckHandle  uint32
-	Unk0       uint16
-	Unk1       uint16
 	CampaignID uint32
 }
 
@@ -24,8 +22,8 @@ func (m *MsgMhfEnumerateItem) Opcode() network.PacketID {
 // Parse parses the packet from binary
 func (m *MsgMhfEnumerateItem) Parse(bf *byteframe.ByteFrame, ctx *clientctx.ClientContext) error {
 	m.AckHandle = bf.ReadUint32()
-	m.Unk0 = bf.ReadUint16()
-	m.Unk1 = bf.ReadUint16()
+	bf.ReadUint16() // Zeroed
+	bf.ReadUint16() // Always 2
 	m.CampaignID = bf.ReadUint32()
 	return nil
 }