J3 D8-prereq: split compact flag so sim drives the picker

Adds inlineBossCombat alongside compact in runAutopilotWalk and
advanceOnceWithOpts. Production background autorun keeps both true
(inline auto-resolve), foreground stays both false (manual !fight), the
sim now uses compact=true + inlineBossCombat=false so the boss/elite
doorway returns stopBoss/stopElite after the safety gate — autoResolveCombat
+ simPickCombatAction / simPickSpell drive the fight via the turn-based
engine. The picker (and D8-b upcasting) has been dead since D3's
compact-inline boss rooms; this re-wires it.

n=50/cell L10 smoke vs d7d (zones T1-T3):
  bard    forest_shadows  61 → 100   (+39)
  bard    manor_blackspire 10 →  34   (+24)
  cleric  forest_shadows  15 →  96   (+81)
  cleric  manor_blackspire 0 →  54   (+54)
  fighter T1-T3                100   (unchanged)

Also parallelizes matrix mode via subprocess workers (each child has its
own SQLite — db package globals preclude in-process parallelism). New
-jobs flag, defaults to runtime.NumCPU(). 8 workers gave ~7x speedup on
the smoke matrix.

internal/plugin/dnd_expedition_cmd.go

@@ -642,7 +642,7 @@ type autopilotWalkResult struct {
 // combat already auto-resolves inside resolveCombatRoom; elite/boss
 // doorways stop here so the player can choose !fight on their own terms.
 func (p *AdventurePlugin) expeditionCmdRun(ctx MessageContext) error {
-	r := p.runAutopilotWalk(ctx, autopilotRoomCap, false)
+	r := p.runAutopilotWalk(ctx, autopilotRoomCap, false, false)
 	if r.initErr != "" {
 		return p.SendDM(ctx.Sender, r.initErr)
 	}
@@ -667,7 +667,7 @@ func (p *AdventurePlugin) expeditionCmdRun(ctx MessageContext) error {
 // run graph / harvest tally / supplies / threat — same as before, just
 // no streamFlow here. compact==true switches the underlying combat
 // narration into terse mode and auto-resolves elite (not boss) rooms.
-func (p *AdventurePlugin) runAutopilotWalk(ctx MessageContext, maxRooms int, compact bool) autopilotWalkResult {
+func (p *AdventurePlugin) runAutopilotWalk(ctx MessageContext, maxRooms int, compact, inlineBossCombat bool) autopilotWalkResult {
 	exp, err := getActiveExpedition(ctx.Sender)
 	if err != nil {
 		return autopilotWalkResult{initErr: "Couldn't read expedition state: " + err.Error()}
@@ -717,7 +717,7 @@ func (p *AdventurePlugin) runAutopilotWalk(ctx MessageContext, maxRooms int, com
 			}
 		}
 
-		res, aerr := p.advanceOnceWithOpts(ctx, compact)
+		res, aerr := p.advanceOnceWithOpts(ctx, compact, inlineBossCombat)
 		if aerr != nil {
 			return autopilotWalkResult{initErr: aerr.Error()}
 		}

internal/plugin/dnd_zone_cmd.go

@@ -472,10 +472,17 @@ func (p *AdventurePlugin) zoneCmdAdvance(ctx MessageContext) error {
 // doorways (boss still stops; boss is the climax beat). Foreground
 // `!expedition run` / `!zone advance` always pass false.
 func (p *AdventurePlugin) advanceOnce(ctx MessageContext) (advanceResult, error) {
-	return p.advanceOnceWithOpts(ctx, false)
+	return p.advanceOnceWithOpts(ctx, false, false)
 }
 
-func (p *AdventurePlugin) advanceOnceWithOpts(ctx MessageContext, compact bool) (advanceResult, error) {
+// inlineBossCombat (only consulted when compact==true) selects between the
+// two background combat paths at a boss/elite doorway. true keeps the
+// long-expedition D3 inline auto-resolve (production autorun). false
+// returns stopBoss/stopElite after the safety gate so a turn-based driver
+// — currently only the headless sim's autoResolveCombat / simPickCombatAction
+// — handles the fight via the regular !fight / !attack engine. The sim
+// uses false so simPickSpell actually fires; D8-prereq re-wired this seam.
+func (p *AdventurePlugin) advanceOnceWithOpts(ctx MessageContext, compact, inlineBossCombat bool) (advanceResult, error) {
 	run, err := getActiveZoneRun(ctx.Sender)
 	if err != nil {
 		return advanceResult{}, fmt.Errorf("Couldn't read run state: %s", err.Error())
@@ -560,6 +567,17 @@ func (p *AdventurePlugin) advanceOnceWithOpts(ctx MessageContext, compact bool)
 					}, nil
 				}
 			}
+			if !inlineBossCombat {
+				// Background caller wants to drive the fight itself (sim's
+				// autoResolveCombat / simPickCombatAction). Surface the
+				// doorway like the foreground path does, after the safety
+				// gate has had a chance to defer the engagement.
+				r := stopElite
+				if prev == RoomBoss {
+					r = stopBoss
+				}
+				return advanceResult{reason: r}, nil
+			}
 			// Compact-mode elite/boss auto-resolve. resolveCombatRoom
 			// selects monster + label by run.CurrentRoomType().
 			ai, ap, ao, aended, aerr := p.resolveCombatRoom(ctx.Sender, run, zone, prev == RoomElite, true)

internal/plugin/expedition_autorun.go

@@ -170,7 +170,7 @@ func (p *AdventurePlugin) tryAutoRun(e *Expedition, now time.Time) error {
 	}
 
 	uid := id.UserID(e.UserID)
-	r := p.runAutopilotWalk(MessageContext{Sender: uid}, autoRunRoomCap, true)
+	r := p.runAutopilotWalk(MessageContext{Sender: uid}, autoRunRoomCap, true, true)
 	if r.initErr != "" {
 		// "no expedition" / "no run" — race with abandon/extract. Silent.
 		return nil

internal/plugin/expedition_sim.go

@@ -429,7 +429,7 @@ func (s *SimRunner) RunExpedition(uid id.UserID, zoneID ZoneID, walkCap, maxDays
 
 	for i := 0; i < walkCap; i++ {
 		simNow = simNow.Add(simWalkInterval)
-		walk := s.P.runAutopilotWalk(ctx, autopilotRoomCap, true)
+		walk := s.P.runAutopilotWalk(ctx, autopilotRoomCap, true, false)
 		if walk.initErr != "" {
 			res.Outcome = "halted"
 			res.StopCode = "init:" + walk.initErr