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/combat_cmd.go

@@ -489,6 +489,14 @@ func (p *AdventurePlugin) handleCombatCastCmd(ctx MessageContext, args string) e
 			PlayerHeal:  out.PlayerHeal,
 			EnemySkip:   out.EnemySkip,
 		}
+		// Concentration AOE damage spells linger: the burst lands this round
+		// (EnemyDamage) and the same value re-ticks every round_end after, via
+		// the engine's concentration aura. spiritual_weapon already covers the
+		// cleric's bonus-action half of the combo; this restores the action half.
+		if spell.Concentration &&
+			(spell.Effect == EffectDamageAuto || spell.Effect == EffectDamageSave) {
+			eff.ConcentrationDmg = out.EnemyDamage
+		}
 	}
 
 	events, err := runCombatRound(sess, &player, &enemy, PlayerAction{Kind: ActionCast, Effect: eff})