Lift caster trailers: concentration re-tick + Josie caster-aid bootstraps

Diagnosed a cleric "death loop" (L14 dying at T2/T3 bosses while
over-levelled): the boss isn't overtuned — caster sustained DPS is
under-delivered, compounded by a fragile healer build.

Engine fix — concentration AOE re-tick:
- Concentration damage spells (spirit_guardians, heat_metal, spike_growth,
  call_lightning, flaming_sphere) now tick the enemy every round at
  round_end instead of resolving as a one-shot, via a new
  CombatStatuses.ConcentrationDmg armed on cast and round-tripped through
  the turn engine. Closes the long-tracked turn-engine concentration gap;
  the burst still lands the casting round, then the aura lingers.
- Sim picker skips re-casting an already-active aura (models competent play
  and prevents a burst+aura double-dip). Re-baseline (n=30 sweep + n=100
  confirm): bard +47pp T3 (heat_metal), druid +3-7, cleric/mage flat,
  fighter unchanged — no regressions.

Player-data bootstraps (idempotent, run once on Init):
- bootstrapCasterSpellBackfill: ensureSpellsForCharacter only seeds an empty
  book, so defaults added after a character's roll never reach it. Backfill
  missing defaults into known+prepared for existing casters (gives the
  affected cleric inflict_wounds + a working healing_word, since her
  healing_word_spell is a dead alias).
- bootstrapGrantStarterPet: one-off L10 pet for an endgame player who never
  got the morning arrival roll; adds per-round proc damage + deflect.
- TestScenario_JosieCasterAid verifies both against a copy of the live DB,
  incl. idempotency.

Also fix a pre-existing wall-clock flake in
TestFireBriefings_EventAnchoredActivePlayerDelivers (start_date defaulted to
real now, filtering the row out when the suite runs after 06:00 UTC).

internal/plugin/dnd_expedition_cycle_test.go

@@ -239,19 +239,26 @@ func TestFireBriefings_EventAnchoredActivePlayerDelivers(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	useEventAnchored(t, exp)
-
 	wall := time.Now().UTC()
 	now := time.Date(wall.Year(), wall.Month(), wall.Day(), 6, 30, 0, 0, time.UTC)
 	threshold := time.Date(now.Year(), now.Month(), now.Day(),
 		expeditionBriefingHour, 0, 0, 0, time.UTC)
 	activeActivity := threshold.Add(15 * time.Minute)
 	priorBriefing := now.Add(-24 * time.Hour)
+	// Pin start_date before today's threshold. Left at the default (real
+	// time.Now()), a suite run after 06:00 UTC lands start_date past the
+	// threshold and loadExpeditionsNeedingBriefing (start_date < threshold)
+	// filters the row out — a wall-clock-of-day flake. useEventAnchored runs
+	// after, so its cutoff tracks the backdated start and the run stays
+	// event-anchored.
+	startAt := now.Add(-24 * time.Hour)
+	exp.StartDate = startAt
 	if _, err := db.Get().Exec(
-		`UPDATE dnd_expedition SET last_activity = ?, last_briefing_at = ? WHERE expedition_id = ?`,
-		activeActivity, priorBriefing, exp.ID); err != nil {
+		`UPDATE dnd_expedition SET start_date = ?, last_activity = ?, last_briefing_at = ? WHERE expedition_id = ?`,
+		startAt, activeActivity, priorBriefing, exp.ID); err != nil {
 		t.Fatal(err)
 	}
+	useEventAnchored(t, exp)
 
 	p := &AdventurePlugin{}
 	p.fireExpeditionBriefings(now)