Coop: lock combat actions for the full duration of an active run

Players in a co-op were getting their combat action back every midnight
reset and offered the dungeon option in the morning DM. Per spec they
should be "off in the Co-op" and unable to also solo-grind dungeons.

Fix at the DB layer (so all CanDoCombat() paths agree):
- New helper lockCoopCombatActions() sets combat_actions_used=99 for any
  user in an active coop run. Called immediately after every
  resetAllAdvDailyActions() — at startup and at midnight.
- Render layer: morning DM now shows "combat locked (in Co-op #N, day
  X/Y)" and replaces the dungeon section with an explanatory line
  pointing them at !coop status.

Combat returns to normal automatically once the run completes/wipes —
the next midnight reset finds status != 'active' and skips the lock.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

internal/plugin/adventure_render.go

@@ -283,11 +283,26 @@ func renderAdvMorningDM(char *AdventureCharacter, equip map[EquipmentSlot]*AdvEq
 		harvestMax++
 	}
 	combatLeft := combatMax - char.CombatActionsUsed
+	if combatLeft < 0 {
+		combatLeft = 0
+	}
 	harvestLeft := harvestMax - char.HarvestActionsUsed
-	sb.WriteString(fmt.Sprintf("📋 **Actions:** %d/%d combat · %d/%d harvest\n\n", combatLeft, combatMax, harvestLeft, harvestMax))
+
+	// Co-op participants have combat locked for the duration of the run.
+	coopRun, _ := loadCoopRunForUser(char.UserID)
+	inCoop := coopRun != nil && coopRun.Status == "active"
+
+	if inCoop {
+		sb.WriteString(fmt.Sprintf("📋 **Actions:** combat locked (in Co-op #%d, day %d/%d) · %d/%d harvest\n\n",
+			coopRun.ID, coopRun.CurrentDay, coopRun.TotalDays, harvestLeft, harvestMax))
+	} else {
+		sb.WriteString(fmt.Sprintf("📋 **Actions:** %d/%d combat · %d/%d harvest\n\n", combatLeft, combatMax, harvestLeft, harvestMax))
+	}
 
 	// Location choices
-	if char.CanDoCombat(isHol) {
+	if inCoop {
+		sb.WriteString(fmt.Sprintf("**1️⃣ Dungeon:** _(off in the Co-op, no solo combat — `!coop status` for run state)_\n"))
+	} else if char.CanDoCombat(isHol) {
 		sb.WriteString("**1️⃣ Dungeon:**\n")
 		for _, el := range advEligibleLocations(char, equip, AdvActivityDungeon, bonuses) {
 			warn := ""