feat: Enhance interaction and inventory systems with new components and functionality

- Added BPC_UsableWorldObjectSystem for handling various interactable world objects with detailed manual implementation guide.
- Introduced BPC_ActiveItemSystem to manage quick slots and active item usage, including cycling and selection logic.
- Implemented BPC_DocumentArchiveSystem for managing collectible documents with read tracking and categorization.
- Developed BPC_JournalSystem for narrative entries with auto-adding features based on gameplay events.
- Created BPC_KeyItemSystem for key management with consumable and persistent key support.
- Enhanced BPC_FirearmSystem for ranged weapon mechanics, including hitscan and projectile firing.
- Updated BPC_MeleeSystem for melee combat with combo and blocking mechanics.
- Established BPC_ReloadSystem for managing weapon reloading processes, including partial reloads and state management.

docs/blueprints/04-inventory/29_BPC_DocumentArchiveSystem.md

@@ -46,4 +46,129 @@
 | `BPC_LoreUnlockSystem` | Lore document triggers |
 
 ## 6. Reuse Notes
-- Documents are inventory items with `E_ItemCategory = Document`
+- Documents are inventory items with `E_ItemCategory = Document`
+
+---
+
+## 7. Manual Implementation Guide
+
+### 7.1 Class Setup
+1. Create Blueprint Class: Parent = `ActorComponent`, Name = `BPC_DocumentArchiveSystem`
+2. Add to Player Character
+3. Define struct `S_DocumentEntry` with fields: `DocumentID` (Guid), `DocumentTag` (GameplayTag), `Title` (Text), `Body` (Text), `Category` (Enum), `bIsRead` (Boolean), `DateCollected` (Float), `bIsFlagged` (Boolean)
+
+### 7.2 Variable Initialization (BeginPlay)
+```
+Event BeginPlay
+  ├─ Set CollectedDocuments = empty Array<S_DocumentEntry>
+  ├─ Set UnreadCount = 0
+  ├─ Set bShowUnreadBadge = true
+  ├─ Get Owner → Find Component by Class (BPC_InventorySystem) → Cache
+  │    └─ Bind to OnItemAdded → OnItemAddedHandler
+  └─ Get Owner → Find BP_DocumentArchiveSystem → self (ensure only one)
+```
+
+### 7.3 Function Implementations
+
+#### `AddDocument(ItemData: DA_ItemData)` → `Boolean`
+
+```
+[Function: AddDocument]
+  Step 1: Branch on ItemData.ItemType == Document → If not, return false
+  Step 2: Check if document with same ItemTag already in CollectedDocuments:
+    ForEach CollectedDocuments → if Entry.DocumentTag == ItemData.ItemTag:
+      Return false (already collected)
+  Step 3: Create S_DocumentEntry struct:
+    - DocumentID = New Guid
+    - DocumentTag = ItemData.ItemTag
+    - Title = ItemData.DisplayName
+    - Body = ItemData.Description  (document content)
+    - Category = determine from tag (ItemTag starts with "Document.Notes" → Notes, etc.)
+    - bIsRead = false
+    - DateCollected = Get Game Time in Seconds
+    - bIsFlagged = false
+  Step 4: Add to CollectedDocuments array
+  Step 5: UnreadCount += 1
+  Step 6: Fire OnDocumentCollected(NewEntry)
+  Step 7: Also notify BPC_LoreUnlockSystem if category is Lore
+  Step 8: Return true
+```
+
+**Nodes:** `New Guid`, `Make S_DocumentEntry`, `Add`, `Get Game Time in Seconds`, `Starts With (String)`
+
+#### `MarkAsRead(DocumentID: Guid)` → `void`
+
+```
+[Function: MarkAsRead]
+  Step 1: Find document in CollectedDocuments by DocumentID:
+    ForEach with Break → if Entry.DocumentID == DocumentID:
+      Branch on Entry.bIsRead:
+        False → Set bIsRead = true, UnreadCount -= 1
+        True → Return (already read)
+  Step 2: Fire OnDocumentRead(DocumentID)
+  Step 3: Branch on UnreadCount == 0:
+    True → Fire OnAllDocumentsRead
+```
+
+#### `MarkAllAsRead()` → `void`
+
+```
+[Function: MarkAllAsRead]
+  Step 1: ForEach CollectedDocuments:
+    Set bIsRead = true
+  Step 2: Set UnreadCount = 0
+  Step 3: Fire OnAllDocumentsRead
+```
+
+#### `GetDocumentsByCategory(Category: E_DocumentCategory, bUnreadOnly: Boolean)` → `Array<S_DocumentEntry>`
+
+```
+[Function: GetDocumentsByCategory] (Pure)
+  Step 1: Create empty Array → Results
+  Step 2: ForEach CollectedDocuments:
+    If Entry.Category == Category AND (NOT bUnreadOnly OR NOT Entry.bIsRead):
+      Add to Results
+  Step 3: Return Results
+```
+
+#### `GetUnreadCount()` → `Integer`
+
+```
+[Function: GetUnreadCount] (Pure)
+  Return UnreadCount
+```
+
+#### `HasDocument(DocumentTag: GameplayTag)` → `Boolean`
+
+```
+[Function: HasDocument] (Pure)
+  Step 1: ForEach CollectedDocuments:
+    If Entry.DocumentTag == DocumentTag → Return true
+  Step 2: Return false
+```
+
+#### `ToggleFlag(DocumentID: Guid)` → `void`
+
+```
+[Function: ToggleFlag]
+  Step 1: Find document by DocumentID in CollectedDocuments
+  Step 2: Entry.bIsFlagged = NOT Entry.bIsFlagged
+  Step 3: If flagged → move to top of array (optional sorting)
+```
+
+### 7.4 Event Dispatcher Bindings
+| Bind to Dispatcher | Custom Event | Logic |
+|-------------------|-------------|-------|
+| `BPC_InventorySystem.OnItemAdded(Item)` | `OnItemAddedHandler` | If Item.ItemData.ItemType == Document → Call AddDocument(Item.ItemData) |
+
+### 7.5 Blueprint Build Checklist
+- [ ] Define enum `E_DocumentCategory`: Notes, Letters, Audio, Data, Photos
+- [ ] Define struct `S_DocumentEntry` with all fields
+- [ ] Create BPC_DocumentArchiveSystem, add to Player Character
+- [ ] Add variables: CollectedDocuments, DocumentCategories, bShowUnreadBadge, UnreadCount
+- [ ] Implement AddDocument with duplicate check and struct creation
+- [ ] Implement MarkAsRead with UnreadCount tracking
+- [ ] Implement GetDocumentsByCategory with optional unread filter
+- [ ] Implement HasDocument for narrative queries
+- [ ] Bind to BPC_InventorySystem.OnItemAdded
+- [ ] Test: pick up document item → archive updates → UI shows badge