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_apply_campaign.go

@@ -2,6 +2,7 @@ package mhfpacket
 
 import (
 	"errors"
+	"erupe-ce/common/bfutil"
 	"erupe-ce/common/byteframe"
 	"erupe-ce/network"
 	"erupe-ce/network/clientctx"
@@ -9,10 +10,9 @@ import (
 
 // MsgMhfApplyCampaign represents the MSG_MHF_APPLY_CAMPAIGN
 type MsgMhfApplyCampaign struct {
-	AckHandle uint32
-	Unk0      uint32
-	Unk1      uint16
-	Unk2      []byte
+	AckHandle  uint32
+	CampaignID uint32
+	Code       string
 }
 
 // Opcode returns the ID associated with this packet type.
@@ -23,9 +23,9 @@ func (m *MsgMhfApplyCampaign) Opcode() network.PacketID {
 // Parse parses the packet from binary
 func (m *MsgMhfApplyCampaign) Parse(bf *byteframe.ByteFrame, ctx *clientctx.ClientContext) error {
 	m.AckHandle = bf.ReadUint32()
-	m.Unk0 = bf.ReadUint32()
-	m.Unk1 = bf.ReadUint16()
-	m.Unk2 = bf.ReadBytes(16)
+	m.CampaignID = bf.ReadUint32()
+	bf.ReadUint16() // Zeroed
+	m.Code = string(bfutil.UpToNull(bf.ReadBytes(16)))
 	return nil
 }