Restore expedition completion on zone clear (lost in merge)

finalizeExpeditionOnZoneClear and its wiring into the run-complete seam
were introduced in 73b7809 but that commit never made it into the
current history — it's not an ancestor of HEAD, so the function, its
call site in advanceOnceWithOpts, and its tests were all absent.

Symptom: clearing a zone (boss down, no outgoing edges) set the run's
boss_defeated flag but never flipped the wrapping expedition to
'complete' or retired the run. The expedition sat 'active' pointing at a
boss_defeated run, so getActiveZoneRun (filters boss_defeated=0) returned
nil and the next '!expedition run' errored with 'No active zone run'. The
ambient ticker also kept DMing about a finished dungeon.

Re-apply the bridge verbatim against current HEAD (deps verified present:
IsMultiRegionZone / CurrentRegion / MarkRegionBossDefeated /
completeExpedition / retireAllRegionRuns / AwardCompletionMilestones) and
restore the test.

internal/plugin/dnd_expedition_zone_clear_test.go

@@ -0,0 +1,116 @@
+package plugin
+
+import (
+	"testing"
+
+	"maunium.net/go/mautrix/id"
+)
+
+// Single-region zone: clearing the run completes the wrapping expedition
+// and flips BossDefeated.
+func TestFinalizeExpeditionOnZoneClear_SingleRegionCompletes(t *testing.T) {
+	setupZoneRunTestDB(t)
+	uid := id.UserID("@zclear-single:example.org")
+	defer cleanupExpeditions(uid)
+
+	exp, err := startExpedition(uid, ZoneSunkenTemple, "run-1",
+		ExpeditionSupplies{Max: 10, Current: 10, DailyBurn: 1})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if exp.RunID != "run-1" {
+		t.Fatalf("setup: RunID = %q", exp.RunID)
+	}
+
+	p := &AdventurePlugin{}
+	p.finalizeExpeditionOnZoneClear(uid, "run-1")
+
+	if act, _ := getActiveExpedition(uid); act != nil {
+		t.Fatalf("expedition still active after zone clear: status=%s", act.Status)
+	}
+	loaded, _ := getExpedition(exp.ID)
+	if loaded.Status != ExpeditionStatusComplete {
+		t.Errorf("status = %q, want %q", loaded.Status, ExpeditionStatusComplete)
+	}
+	if !loaded.BossDefeated {
+		t.Error("BossDefeated not set after single-region zone clear")
+	}
+}
+
+// A run that isn't the expedition's current run must not complete it.
+func TestFinalizeExpeditionOnZoneClear_RunMismatchNoop(t *testing.T) {
+	setupZoneRunTestDB(t)
+	uid := id.UserID("@zclear-mismatch:example.org")
+	defer cleanupExpeditions(uid)
+
+	exp, err := startExpedition(uid, ZoneSunkenTemple, "run-1",
+		ExpeditionSupplies{Max: 10, Current: 10, DailyBurn: 1})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	p := &AdventurePlugin{}
+	p.finalizeExpeditionOnZoneClear(uid, "some-other-run")
+
+	loaded, _ := getExpedition(exp.ID)
+	if loaded.Status != ExpeditionStatusActive {
+		t.Errorf("status = %q, want active (mismatched run should be no-op)", loaded.Status)
+	}
+}
+
+// Multi-region zone: clearing a non-boss region marks it cleared but leaves
+// the expedition active so inter-region travel can continue.
+func TestFinalizeExpeditionOnZoneClear_MidZoneRegionStaysActive(t *testing.T) {
+	setupZoneRunTestDB(t)
+	uid := id.UserID("@zclear-midzone:example.org")
+	defer cleanupExpeditions(uid)
+
+	// CurrentRegion defaults to the first region (underdark_surface_tunnels,
+	// not the zone boss).
+	exp, err := startExpedition(uid, ZoneUnderdark, "run-1",
+		ExpeditionSupplies{Max: 10, Current: 10, DailyBurn: 1})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	p := &AdventurePlugin{}
+	p.finalizeExpeditionOnZoneClear(uid, "run-1")
+
+	loaded, _ := getExpedition(exp.ID)
+	if loaded.Status != ExpeditionStatusActive {
+		t.Errorf("status = %q, want active after non-boss region clear", loaded.Status)
+	}
+	if !IsRegionCleared(loaded, "underdark_surface_tunnels") {
+		t.Error("first region not marked cleared")
+	}
+	if loaded.BossDefeated {
+		t.Error("BossDefeated set on a non-boss region clear")
+	}
+}
+
+// Multi-region zone: clearing the zone-boss region completes the expedition.
+func TestFinalizeExpeditionOnZoneClear_ZoneBossRegionCompletes(t *testing.T) {
+	setupZoneRunTestDB(t)
+	uid := id.UserID("@zclear-zoneboss:example.org")
+	defer cleanupExpeditions(uid)
+
+	exp, err := startExpedition(uid, ZoneUnderdark, "run-1",
+		ExpeditionSupplies{Max: 10, Current: 10, DailyBurn: 1})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := setCurrentRegion(exp, "underdark_deep_throne"); err != nil {
+		t.Fatal(err)
+	}
+
+	p := &AdventurePlugin{}
+	p.finalizeExpeditionOnZoneClear(uid, "run-1")
+
+	loaded, _ := getExpedition(exp.ID)
+	if loaded.Status != ExpeditionStatusComplete {
+		t.Errorf("status = %q, want complete after zone-boss region clear", loaded.Status)
+	}
+	if !loaded.BossDefeated {
+		t.Error("BossDefeated not set after zone-boss region clear")
+	}
+}