Implement the 014-inline-hp-delta feature that replaces the damage/heal mode toggle with explicit action buttons and Enter-to-damage keyboard shortcut

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

specs/014-inline-hp-delta/data-model.md

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+# Data Model: Inline HP Delta Input
+
+## No data model changes
+
+This feature does not modify any domain entities, events, or state transitions. The existing data model fully supports the new UI:
+
+### Existing Entities (unchanged)
+
+**Combatant**
+- `id`: CombatantId (branded string)
+- `name`: string
+- `initiative?`: number
+- `maxHp?`: number
+- `currentHp?`: number
+
+**Encounter**
+- `combatants`: readonly Combatant[]
+- `activeIndex`: number
+- `roundNumber`: number
+
+### Existing Domain Function (unchanged)
+
+**adjustHp(encounter, combatantId, delta) -> AdjustHpSuccess | DomainError**
+- Negative delta = damage, positive delta = heal
+- Clamps result to [0, maxHp]
+- Emits `CurrentHpAdjusted` event
+
+### Existing Domain Event (unchanged)
+
+**CurrentHpAdjusted**
+- `combatantId`: CombatantId
+- `previousHp`: number
+- `newHp`: number
+- `delta`: number
+
+### UI State Changes
+
+The only state change is in the QuickHpInput component:
+- **Removed**: `mode: "damage" | "heal"` state variable
+- **Kept**: `value: string` state variable for the input field
+
+The action (damage vs heal) is now determined at invocation time by which button/key triggered it, not by a stored mode.