Review follow-ups: harden the extraction guard, fix Misty/concentration ordering

Applying /code-review high findings on the review-follow-up stack:

- expeditionCmdStart: the resumable-extraction guard swallowed a partySize
  error and fell open, starting a new expedition on top of a still-seated
  party — the exact orphaning it exists to prevent. Now checks
  extractionLapsed first (no DB call on the reap path) and treats a
  roster-read error as "assume occupied → refuse".
- Lapsed reap on !expedition start silently unseated members. Extracted a
  shared reapLapsedExtraction helper (reap + notify the roster) and routed
  both the hourly sweeper and the start-path reap through it.
- stepRoundEnd: moved Misty's crowd/heal seat-loop after the concentration
  tick so a caster whose lingering aura would kill the enemy that round wins
  before the end-of-round crowd swing, honoring the concentration block's
  "a lethal pulse settles the fight" intent.
- Promoted the misty_heal event-log scan to a shared hasAction helper.
- Renamed the new sweep test off the dnd_ prefix.

Claude-Session: https://claude.ai/code/session_017mEwUmmS7aQTP2NQXj6rUa

internal/plugin/dnd_expedition_extract.go

@@ -252,9 +252,6 @@ func loadLapsedExtractions(now time.Time) ([]*Expedition, error) {
 // status) never runs. Every member stays seated, and assertNotAdventuring keeps
 // refusing them a run of their own. `!expedition leave` is their escape, but a
 // player should not have to find it.
-//
-// The audience is read before the close-out: completeExpedition disbands the
-// roster, and expeditionAudience reads that roster.
 func (p *AdventurePlugin) sweepLapsedExtractions(now time.Time) {
 	exps, err := loadLapsedExtractions(now)
 	if err != nil {
@@ -262,21 +259,36 @@ func (p *AdventurePlugin) sweepLapsedExtractions(now time.Time) {
 		return
 	}
 	for _, e := range exps {
-		audience := expeditionAudience(e)
-		if err := completeExpedition(e.ID, ExpeditionStatusFailed); err != nil {
+		if err := p.reapLapsedExtraction(e); err != nil {
 			slog.Warn("expedition: expire lapsed extraction", "expedition", e.ID, "err", err)
 			continue
 		}
-		zone, _ := getZone(e.ZoneID)
-		body := fmt.Sprintf(
-			"🕯 **The way back has closed — %s**\n\nYour extracted expedition sat past its seven-day resume window, and the dungeon reshaped without you. Day %d is where it ends.\n\nThe loot, XP, and coins you carried out are still yours. `!expedition list` when you're ready for the next one.",
-			zone.Display, e.CurrentDay)
-		for _, uid := range audience {
-			if err := p.SendDM(uid, body); err != nil {
-				slog.Warn("expedition: lapsed-extraction DM failed", "user", uid, "expedition", e.ID, "err", err)
-			}
+	}
+}
+
+// reapLapsedExtraction closes one lapsed extraction and tells its roster the
+// way back has shut. It is the single reap-with-notify path: the hourly
+// sweeper loops it, and expeditionCmdStart calls it when a player starts a new
+// expedition on top of one whose window has already closed — so a member is
+// never silently unseated by whichever path happens to reach the row first.
+//
+// The audience is read before the close-out: completeExpedition disbands the
+// roster, and expeditionAudience reads that roster.
+func (p *AdventurePlugin) reapLapsedExtraction(e *Expedition) error {
+	audience := expeditionAudience(e)
+	if err := completeExpedition(e.ID, ExpeditionStatusFailed); err != nil {
+		return err
+	}
+	zone, _ := getZone(e.ZoneID)
+	body := fmt.Sprintf(
+		"🕯 **The way back has closed — %s**\n\nYour extracted expedition sat past its seven-day resume window, and the dungeon reshaped without you. Day %d is where it ends.\n\nThe loot, XP, and coins you carried out are still yours. `!expedition list` when you're ready for the next one.",
+		zone.Display, e.CurrentDay)
+	for _, uid := range audience {
+		if err := p.SendDM(uid, body); err != nil {
+			slog.Warn("expedition: lapsed-extraction DM failed", "user", uid, "expedition", e.ID, "err", err)
 		}
 	}
+	return nil
 }
 
 // expeditionExtractionSweepTicker reaps lapsed extractions hourly. The window is