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/dnd_test.go

@@ -58,10 +58,11 @@ func TestIsStandardArray(t *testing.T) {
 }
 
 func TestComputeMaxHP_FighterLevel1(t *testing.T) {
-	// Fighter d10, CON +2 → L1 HP = 10 + 2 = 12
+	// Fighter d10, CON +2 → L1 raw HP = 10 + 2 = 12; Phase 5-B
+	// multiplies by phase5BHPMult (1.5, rounded), so → 18.
 	got := computeMaxHP(ClassFighter, 2, 1)
-	if got != 12 {
-		t.Errorf("Fighter L1 (CON+2) = %d, want 12", got)
+	if got != 18 {
+		t.Errorf("Fighter L1 (CON+2) = %d, want 18 (12 raw × phase5BHPMult)", got)
 	}
 }
 
@@ -69,10 +70,10 @@ func TestComputeMaxHP_MageLevel5(t *testing.T) {
 	// Mage d6, CON +1
 	// L1: 6 + 1 = 7
 	// L2-5: 4 levels × (avg 4 + 1) = 4 × 5 = 20
-	// Total: 27
+	// Raw total: 27; Phase 5-B: 27 × 1.5 = 40.5 → 41 (round half-up).
 	got := computeMaxHP(ClassMage, 1, 5)
-	if got != 27 {
-		t.Errorf("Mage L5 (CON+1) = %d, want 27", got)
+	if got != 41 {
+		t.Errorf("Mage L5 (CON+1) = %d, want 41 (27 raw × phase5BHPMult)", got)
 	}
 }