N7/B3: the Omen — one rotating world modifier per ISO week

activeOmen() is a pure function of the UTC ISO (year, week): omenTable
indexed by (year*53+week)%len, so it advances weekly with no schema, no
ticker state, no persistence. Five non-combat seams read it — harvest yield,
supply freebie, expedition start mood, arena payout (scales gross earnings
before the pot tax), and ingredient drop chance. TwinBee reveals the active
omen in the existing morning DM (no net-new scheduled message).

Launch set is buffs-with-texture on non-combat levers only: Bountiful
Harvest, Quartermaster's Blessing, Golden Purse, Overflowing Satchels, Still
Waters. Nothing touches SimulateCombat or the turn engine — the omen is keyed
on the real clock, so a combat mutator would make the golden and the balance
corpus week-dependent. The plan's "elites +2 ATK" is deliberately dropped for
that reason.

The balance sim drives the real expedition loop and would otherwise traverse
all five seams, making corpus sweeps depend on the wall-clock week. NewSimRunner
sets simOmenDisabled (mirrors simAutoArmEnabled), so activeOmen returns a
no-effect omen under the sim. Still Waters subtracts from the daily threat
*rise* only, floored at hold-steady — it never forces active decay.

Claude-Session: https://claude.ai/code/session_017mEwUmmS7aQTP2NQXj6rUa

internal/plugin/adventure_render.go

@@ -312,6 +312,12 @@ func renderAdvMorningDM(userID id.UserID, equip map[EquipmentSlot]*AdvEquipment,
 		sb.WriteString(fmt.Sprintf("🎉 Happy %s! In recognition of %s, today's adventures come with TwinBee's blessing — new zone & expedition runs start at +5 mood, expedition outfitting includes a complimentary standard pack, and every harvest yields one extra unit.\n\n", holidayName, holidayName))
 	}
 
+	// N7/B3 the Omen — this week's world modifier, in TwinBee's voice. Rides the
+	// existing morning DM (no net-new scheduled message); persistent one-liner so
+	// a mid-week arrival still learns the active omen.
+	sb.WriteString(omenMorningLine(activeOmen()))
+	sb.WriteString("\n\n")
+
 	// Pick a morning greeting
 	greeting, _ := advPickFlavor(MorningDM, userID, "morning_dm")
 	displayName, _ := loadDisplayName(userID)