Add campaign bonuses; fix parts variant/sub-stat grants and menu-pick quest resume state

server/internal/campaign/modifier.go

@@ -0,0 +1,57 @@
+package campaign
+
+type RateBonus struct {
+	override    int32
+	bonusPermil int32
+}
+
+func (b RateBonus) Apply(basePermil int32) int32 {
+	base := basePermil
+	if b.override > 0 {
+		base = b.override
+	}
+	return clampPermil(base + b.bonusPermil)
+}
+
+type ExpBonus struct {
+	bonusPermil int32
+}
+
+func (b ExpBonus) Apply(base int32) int32 {
+	return base * (1000 + b.bonusPermil) / 1000
+}
+
+type StaminaMul struct {
+	permil int32
+}
+
+func (m StaminaMul) Apply(base int32) int32 {
+	if m.permil == 1000 {
+		return base
+	}
+	return base * m.permil / 1000
+}
+
+type DropRateMul struct {
+	bonusPermil int32
+}
+
+func (m DropRateMul) Apply(base int32) int32 {
+	return (base*(1000+m.bonusPermil) + 999) / 1000
+}
+
+type BonusDrop struct {
+	PossessionType int32
+	PossessionId   int32
+	Count          int32
+}
+
+func clampPermil(v int32) int32 {
+	if v < 0 {
+		return 0
+	}
+	if v > 1000 {
+		return 1000
+	}
+	return v
+}