feat: implement Room Enchantments system for Enchanter attunement

- Add roomEnchantment field to FloorState (coverage meter 0-100)
- Add 8 room enchantment effect definitions (fire/frost/death/lightning/dark/earth/transference)
- Add room-enchanting discipline with perks (room-coverage-rate capped, resonant-stamps once, 8 unlock perks)
- Add room enchantment combat tick phase (after DoT) with coverage growth and effect application
- Add coverage carryover between rooms via resonant-stamps perk
- Add RoomDisplay coverage bar and effect magnitude UI
- Add room-enchantments-utils.ts for coverage/effect computation
- Extract combat-room-enchantments.ts to keep combat-actions.ts under 400 lines
- Add 25 tests covering all acceptance criteria (AC-1 through AC-22)

src/lib/game/data/disciplines/enchanter-combat.ts

@@ -0,0 +1,102 @@
+// ─── Enchanter Combat Disciplines ──────────────────────────────────────────────
+// Room Enchanting discipline for the Room Enchantments system
+
+import { DisciplinesAttunementType } from '../../types/disciplines';
+import type { DisciplineDefinition } from '../../types/disciplines';
+
+export const enchanterCombatDisciplines: DisciplineDefinition[] = [
+  {
+    id: 'room-enchanting',
+    name: 'Room Enchanting',
+    attunement: DisciplinesAttunementType.ENCHANTER,
+    manaType: 'transference',
+    baseCost: 10,
+    description: 'Empower your footwear enchantments to fill the room with elemental auras during combat. Higher mastery increases aura magnitude.',
+    statBonus: { stat: 'roomEnchantmentAuraMagnitude', baseValue: 0.10, label: 'Room Aura Magnitude' },
+    difficultyFactor: 150,
+    scalingFactor: 100,
+    drainBase: 3,
+    perks: [
+      {
+        id: 'room-coverage-rate',
+        type: 'capped',
+        threshold: 100,
+        value: 150,
+        maxTier: 4,
+        description: '+0.03 coverage/tick per tier (max 4)',
+        bonus: { stat: 'roomCoverageRate', amount: 0.03 },
+      },
+      {
+        id: 'resonant-stamps',
+        type: 'once',
+        threshold: 500,
+        value: 0,
+        description: 'Carry 20% coverage between rooms (max 20%)',
+      },
+      {
+        id: 'room-sigil-fire',
+        type: 'once',
+        threshold: 50,
+        value: 0,
+        description: 'Unlock Blazing Footsteps room enchantment',
+        unlocksEffects: ['boots_sigil_fire'],
+      },
+      {
+        id: 'room-sigil-frost',
+        type: 'once',
+        threshold: 75,
+        value: 0,
+        description: 'Unlock Frozen Trail room enchantment',
+        unlocksEffects: ['boots_sigil_frost'],
+      },
+      {
+        id: 'room-sigil-death',
+        type: 'once',
+        threshold: 100,
+        value: 0,
+        description: 'Unlock Necrotic Tread room enchantment',
+        unlocksEffects: ['boots_sigil_death'],
+      },
+      {
+        id: 'room-sigil-lightning',
+        type: 'once',
+        threshold: 125,
+        value: 0,
+        description: 'Unlock Shocking Stride room enchantment',
+        unlocksEffects: ['boots_sigil_lightning'],
+      },
+      {
+        id: 'room-sigil-dark',
+        type: 'once',
+        threshold: 150,
+        value: 0,
+        description: 'Unlock Shadow Patch room enchantment',
+        unlocksEffects: ['boots_sigil_dark'],
+      },
+      {
+        id: 'room-sigil-earth',
+        type: 'once',
+        threshold: 175,
+        value: 0,
+        description: 'Unlock Scoured Earth room enchantment',
+        unlocksEffects: ['boots_sigil_earth'],
+      },
+      {
+        id: 'room-sigil-transference-ground',
+        type: 'once',
+        threshold: 100,
+        value: 0,
+        description: 'Unlock Transference Grounds room enchantment',
+        unlocksEffects: ['boots_sigil_transference_ground'],
+      },
+      {
+        id: 'room-sigil-transference-path',
+        type: 'once',
+        threshold: 125,
+        value: 0,
+        description: 'Unlock Conductive Path room enchantment',
+        unlocksEffects: ['boots_sigil_transference_path'],
+      },
+    ],
+  },
+];