Phase 5b: player power floor + Phase-3 winners shipped to live

Closes the 'fairly breezy with some death' target the user picked
for Phase 5. Five-piece ship; Phase 1 matrix lands T1 88%, T2 74%,
T4 72%, T5 ~57% in or above band. T3 remains the design hump at
~45% (manor 39, underforge 47) — Wraith promotion to elite was
already done in Phase 4-B, the remaining standard-pool deaths are
the irreducible part of T3.

Pieces:
  1. computeMaxHP × 1.5 (phase5BHPMult in dnd.go). Uniform across
     class/level so the class-balance harness's in-tier parity
     assertion stays green. Bootstrap (bootstrap_phase5b_hp.go)
     refreshes hp_max for existing characters at startup;
     idempotent via db.JobCompleted. hp_current is bumped by the
     same delta so a full-HP character stays at full.
  2. applyPhase5BPlayerFloor (dnd_combat.go): +3 AC, +3 AttackBonus,
     +3 weapon.MagicBonus (damage). Applied at the END of
     applyDnDEquipmentLayer (after computeArmorAC's AC override)
     and inside buildHarnessPlayer so live and harness measurement
     match.
  3. Elite bracket 19 → 23 (resolveCombatInterrupt). Case order
     puts Elite (≥23) before Patrol (≥22) so a 23+ total prefers
     the single dangerous fight. Elite is now effectively a
     high-threat event reachable only via the +1-per-20-threat-
     above-40 mod — Phase 4-B's elite-pool monsters still appear,
     just less often.
  4. dailyThreatDrift base 3 → 1. Slows the threat clock so
     players have the days they need before threat tips zones
     into the new 23+ elite band.
  5. applyDailyBurn default → 50% (phase5BDailyBurnRatePct). Also
     applied in the temporal-override branch in
     dnd_expedition_cycle.go so tidal / unraveling days scale by
     the same 0.5× — otherwise those days would be
     disproportionately harsh against the new baseline.

The harness's expedition_balance.go reads phase5BDailyBurnRatePct
as the default-burn fallback when the override knob is zero, so
Phase 1 matrix measurements now reflect what live players
experience.

Test debt: 13 pinned-numbers unit tests across combat_stats_test,
dnd_test, dnd_xp_test, dnd_equipment_profiles_test,
dnd_expedition_supplies_test, dnd_expedition_cycle_test,
dnd_expedition_extract_test, dnd_expedition_region_cmd_test,
dnd_expedition_combat_test, dnd_expedition_threat_test,
dnd_expedition_temporal_test, expedition_balance_test were
pinning pre-Phase-5-B baselines; updated with comments noting
the cause. Class-balance suite stayed green (uniform buff
preserves spread).

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

internal/plugin/combat_stats_test.go

@@ -276,12 +276,19 @@ func TestBalanceRegression_DungeonDeathRates(t *testing.T) {
 	}
 	// `level` is the dnd_level (CombatLevel is no longer consulted for combat
 	// scaling — gear + dnd sheet drive everything).
+	// Phase 5-B bumped the player power floor (+3 AC, +3 to-hit, +3
+	// damage, HP ×1.5), so well-equipped at-tier players are now
+	// effectively dominant across the board. "Real danger" at T5 is
+	// no longer the gate — the difficulty curve is driven by the
+	// expedition layer (interrupt cadence, supply burn, threat
+	// drift), not 1:1 well-equipped combat. These bounds reflect the
+	// new "fairly breezy with some death" target.
 	cases := []tc{
-		{1, 1, advDungeons[0], 0.05, 0.0},    // T1: trivial with proper gear
-		{2, 2, advDungeons[1], 0.10, 0.0},    // T2: very easy at level
-		{5, 3, advDungeons[2], 0.15, 0.0},    // T3: low risk at level with T3 gear
-		{7, 4, advDungeons[3], 0.25, 0.0},    // T4: some risk even geared
-		{9, 5, advDungeons[4], 0.35, 0.01},   // T5: real danger — monster stats catch up
+		{1, 1, advDungeons[0], 0.03, 0.0},   // T1: trivial with proper gear
+		{2, 2, advDungeons[1], 0.05, 0.0},   // T2: trivial at level
+		{5, 3, advDungeons[2], 0.08, 0.0},   // T3: low risk
+		{7, 4, advDungeons[3], 0.15, 0.0},   // T4: still mostly safe
+		{9, 5, advDungeons[4], 0.25, 0.0},   // T5: occasional bad luck
 	}
 
 	for _, c := range cases {
@@ -333,11 +340,19 @@ func TestBalanceRegression_UnderleveledPlayers(t *testing.T) {
 		minDeath float64
 	}
 	// `level` is dnd_level. Underleveled = dnd_level low for the dungeon tier.
+	// Phase 5-B player floor (+3 AC, +3 to-hit, +3 damage, HP ×1.5)
+	// is a flat bonus that lifts low-level characters proportionally
+	// more than high-level ones — underleveled vs. tier is no longer
+	// the failure mode it was. Real-game pressure on underleveled
+	// players comes from the *expedition* layer (interrupt cadence,
+	// supply burn, threat clock), not from 1:1 combat. Bounds here
+	// only check that combat still terminates and doesn't pin a
+	// difficulty floor that Phase 5-B intentionally removed.
 	cases := []tc{
-		{"L1 in T2 dungeon", 1, 0, advDungeons[1], 0.40},
-		{"L2 in T3 dungeon", 2, 1, advDungeons[2], 0.30},
-		{"L4 in T4 dungeon, T2 gear", 4, 2, advDungeons[3], 0.25},
-		{"L6 in T5 dungeon, T3 gear", 6, 3, advDungeons[4], 0.30},
+		{"L1 in T2 dungeon", 1, 0, advDungeons[1], 0.0},
+		{"L2 in T3 dungeon", 2, 1, advDungeons[2], 0.0},
+		{"L4 in T4 dungeon, T2 gear", 4, 2, advDungeons[3], 0.0},
+		{"L6 in T5 dungeon, T3 gear", 6, 3, advDungeons[4], 0.0},
 	}
 
 	for _, c := range cases {