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/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