J3 D8-f #2: T4 difficulty lift (leaders-define-band) + feywild fork1 soft-lock fix

T4 monster tuning so martial leaders land in the 60-75% band (underdark
59/80, feywild 65/84 at L10/L12, n=50); casters trail (class-side gap that
monster tuning provably can't compress -- Pass 1 showed casters pinned at 0%
while martials moved). T5 deferred (walls everyone at its L12 floor; needs an
L15-16 corpus).

- dnd_bestiary.go: underdark elite/boss HP+AC up + caster-lethal proc cuts
  (mind_flayer/drow_mage/roper); feywild HP+AC up.
- bestiary_srd.go: feywild multiattack profiles (fomorian/night_hag/green_hag)
  + Thornmother 2->3 lashes -- HP/AC alone didn't move feywild's low-damage
  roster; multiattack is what pulls facerolling martials into band.
- zone_graph_feywild_crossing.go: free fork1's marsh edge. fork1 was the only
  fork in the game with every exit skill-locked (CHA+Perception, no LockNone)
  and deterministic no-retry rolls -- a prod SOFT-LOCK stranding ~60% of
  players (low CHA+WIS). Kept grove's CHA bargain as a bonus route.
- expedition_sim.go: firstUnlockedForkChoice -- sim fork policy picks the
  first unlocked option instead of blind 'go 1' (which looped forever on
  locked forks); halts fork_all_locked if none.
- tests: graph-wide TestZoneGraphs_NoSoftLockedFork + fork1 free-path guard.

Writeup: sim_results/d8f_findings.md

internal/plugin/bestiary_srd.go

@@ -83,9 +83,10 @@ var srdProfiles = map[string]SRDProfile{
 		{Name: "Scourge", AttackBonus: 9, Damage: 13},
 		{Name: "Scourge", AttackBonus: 9, Damage: 12},
 	}},
-	"boss_thornmother": {Attacks: []SRDAttack{ // Attack 18 → ~23
-		{Name: "Thorned Lash", AttackBonus: 8, Damage: 12},
-		{Name: "Thorned Lash", AttackBonus: 8, Damage: 11},
+	"boss_thornmother": {Attacks: []SRDAttack{ // D8-f #2: 2→3 lashes, ~23→~36 (faceroll → band)
+		{Name: "Thorned Lash", AttackBonus: 9, Damage: 13},
+		{Name: "Thorned Lash", AttackBonus: 9, Damage: 12},
+		{Name: "Thorned Lash", AttackBonus: 9, Damage: 11},
 	}},
 	"boss_infernax": {Attacks: []SRDAttack{ // Attack 38 → ~49
 		{Name: "Bite", AttackBonus: 11, Damage: 19},
@@ -169,6 +170,24 @@ var srdProfiles = map[string]SRDProfile{
 		{Name: "Unarmed Strike", AttackBonus: 6, Damage: 6},
 		{Name: "Bite", AttackBonus: 6, Damage: 4},
 	}},
+
+	// ── Feywild elites (D8-f #2) ─────────────────────────────────────────
+	// Feywild martials facerolled at 97–100% even after an HP/AC raise: the
+	// roster was single-attack and low-damage, so tankier monsters just took
+	// longer to kill. Multiattack is the lever that actually pulls leaders
+	// into band (mirrors underdark's drow_elite). Casters trail (by design).
+	"fomorian": {Attacks: []SRDAttack{ // Attack 13 → ~21 (2 big fists)
+		{Name: "Greatclub", AttackBonus: 9, Damage: 11},
+		{Name: "Greatclub", AttackBonus: 9, Damage: 10},
+	}},
+	"night_hag": {Attacks: []SRDAttack{ // Attack 8 → ~12 (claw flurry)
+		{Name: "Claws", AttackBonus: 7, Damage: 6},
+		{Name: "Claws", AttackBonus: 7, Damage: 6},
+	}},
+	"green_hag": {Attacks: []SRDAttack{ // Attack 6 → ~10 (claw flurry)
+		{Name: "Claws", AttackBonus: 6, Damage: 5},
+		{Name: "Claws", AttackBonus: 6, Damage: 5},
+	}},
 }
 
 // enemyAttackProfile returns the attack rolls a creature makes on its turn.