Ship-audit P0/P1 sweep on open5e: prose, combat math, UX hygiene

P0 — actual bugs:
- eldritch_blast: SRD-imported "Whatever" placeholder leaked to players;
  overlay added in dnd_spells_data.go.
- Battle Master disarming_attack + parry: math.Max on multiplicative
  DamageReduct was a no-op vs the 1.0 default. Switched to *= and added
  regression tests covering the stacking case too.
- Extended TestSpellDescriptionsAreJargonFree to catch "Whatever",
  trailing ellipses, mid-word truncation, and empty-size phrases. This
  surfaced 4 more genuinely-broken SRD descriptions (find_familiar,
  clairvoyance, glyph_of_warding, teleportation_circle); all now
  overlayed in dnd_spells_data.go.

P1 — UX hygiene:
- Setup completion now nudges new casters toward !spells/!cast.
- Magic-item attunement vocab unified to "bond" everywhere user-facing;
  renamed the Treasures sheet section to avoid clashing with the bond
  vocab.
- Ambient DM footers stripped of "Threat +N" / "Supplies −N SU" hidden-
  meter leakage; verb-form footers instead.
- !expedition status defaults to a days-left + threat-label summary;
  raw SU / threat-out-of-100 / zone-stack / roll-modifier moved behind
  `!expedition status --debug`.
- !zone taunt/compliment help text dropped the "(mood −10)" / "(mood +5)"
  numerics that turned the hidden TwinBee-mood mechanic into a min/max
  knob.
- TwinBee pronoun pass: switched she/her to singular they on the two
  surfaces I touched plus achievements.bj_beat_twinbee.

P1 — correctness/scale:
- adventure_shop curio purchase now guards the euro.Debit bool return
  before inventory grant + pot cut; the GetBalance preflight isn't
  enough since a concurrent blackjack/lottery debit can slip the balance
  across BLACKJACK_DEBT_LIMIT between read and write.
- equipMagicItem reordered: remove inventory item BEFORE equip, with a
  best-effort rollback if equip fails. The prior order left a dup
  window if the inventory delete tripped on a transient DB error.
- magicItemsByRarityCache promoted to sync.Once — concurrent cold-start
  loot rolls otherwise raced on the lazy assignment.

Stale-audit verifications (no code change needed):
- light / druidcraft / water_walk overlays already exist and win the
  SRD merge — the broken raw text never reaches players.
- bootstrapPhase5BHPRefresh is already wired at adventure.go:228.

Deferred:
- combatantsForSession per-turn 6-load DB chatter (perf P1-A): touches
  the hot combat path; needs its own test pass before shipping. Tracked
  in memory at project_combat_session_cache_deferred.

go vet clean; go test -race ./... green (229s).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

internal/plugin/dnd_setup.go

@@ -610,16 +610,26 @@ func renderConfirmPreview(c *DnDCharacter) string {
 func renderSetupComplete(c *DnDCharacter) string {
 	ri, _ := raceInfo(c.Race)
 	ci, _ := classInfo(c.Class)
+	nextLine := "Use `!sheet` anytime to review. `!zone list` to head out, or `!expedition list` for a longer run."
+	if isSpellcaster(c) {
+		// Casters get auto-granted spells on character creation but no
+		// in-game discovery prompt for them. Surface !spells / !cast so
+		// they can actually find their kit. Long-rest refresh is the
+		// other piece they need to know, but that becomes obvious the
+		// moment they look at !spells.
+		nextLine = "Use `!sheet` anytime to review. `!spells` lists what you can cast and `!cast <spell>` does the deed. `!zone list` heads out; `!expedition list` is the longer run."
+	}
 	return fmt.Sprintf(
 		"⚔️ **Character Sheet Forged**\n\n"+
 			"You are a **Level %d %s %s**.\n"+
 			"  HP %d/%d   AC %d\n"+
 			"  STR %d  DEX %d  CON %d  INT %d  WIS %d  CHA %d\n\n"+
 			"_%s_\n\n"+
-			"Use `!sheet` anytime to review. `!zone list` to head out, or `!expedition list` for a longer run.",
+			"%s",
 		c.Level, ri.Display, ci.Display,
 		c.HPCurrent, c.HPMax, c.ArmorClass,
 		c.STR, c.DEX, c.CON, c.INT, c.WIS, c.CHA,
 		ri.Passive,
+		nextLine,
 	)
 }