add blueprints

docs/blueprints/03-interaction/23_BPC_UsableWorldObjectSystem.md

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+# BPC_UsableWorldObjectSystem — Usable World Object System
+
+**Parent Class:** `ActorComponent`
+**Category:** Interaction
+**Target UE Version:** 5.5–5.7
+**Build Phase:** 2 — Interaction
+
+## 1. Overview
+`BPC_UsableWorldObjectSystem` powers generic usable objects in the world — switches, buttons, valves, terminals, readable notes, audio logs. Provides a unified interaction interface for any object the player can "use" via the InteractionDetector.
+
+## 2. Enums
+### `E_UsableObjectType`
+| Value | Description |
+|-------|-------------|
+| `Switch` | Toggleable switch |
+| `Button` | Pressable button |
+| `Valve` | Rotatable valve |
+| `Terminal` | Interactive screen |
+| `Readable` | Note/book |
+| `AudioLog` | Audio playback device |
+| `Generic` | Custom interaction |
+
+## 3. Variables
+| Variable | Type | Description |
+|----------|------|-------------|
+| `ObjectType` | `E_UsableObjectType` | Type of usable object |
+| `InteractionData` | `DA_InteractionData*` | Interaction definition |
+| `bIsActive` | `bool` | Object enabled |
+| `bSingleUse` | `bool` | Can only be used once |
+| `bHasBeenUsed` | `bool` | Tracked if single-use |
+| `CooldownSeconds` | `float` | Reuse cooldown |
+
+## 4. Functions
+| Function | Description |
+|----------|-------------|
+| `OnUse` | Executes interaction logic |
+| `SetEnabled` | Enable/disable object |
+| `ResetObject` | Return to initial state |
+
+## 5. Event Dispatchers
+| Dispatcher | Payload | Description |
+|------------|---------|-------------|
+| `OnObjectUsed` | `AActor* User` | Object successfully used |
+| `OnObjectStateChanged` | `bool bIsActive` | State toggled |
+
+## 6. Dependencies
+| System | Relationship |
+|--------|--------------|
+| `BPC_InteractionDetector` | Focus and interaction routing |
+| `DA_InteractionData` | Data-driven interaction config |
+
+## 7. Reuse Notes
+- Generic base for all "press E to use" world objects
+- Can be subclassed for specialized behavior