feat: Add multiplayer networking architecture and documentation updates

- Updated Master Blueprint Index to include Multiplayer Networking support.
- Added detailed Multiplayer Networking sections across all developer documentation (01-11).
- Introduced authority maps, key patterns, and RPC guidelines for each system.
- Established a comprehensive multiplayer networking architecture document outlining core principles, replication strategies, and anti-cheat considerations.
- Enhanced UI documentation to clarify local-only behavior and binding to replicated dispatchers.
- Implemented client prediction strategies and RPC naming conventions for consistency across the framework.

docs/blueprints/03-interaction/17_I_HidingSpot.md

@@ -283,4 +283,26 @@ sequenceDiagram
 
 ---
 
+## 10. Multiplayer Networking
+
+### Replicated Variables
+| Variable | Condition | Purpose |
+|----------|-----------|---------|
+| `bOccupied` | `Replicated` | Other clients see spot as occupied |
+| `LockedByPlayer` | `Replicated` | Synced lock state |
+| `OccupantPawn` | `Replicated` | Who is hiding here (for third-person visibility) |
+| `bIsVisible` | `Replicated` | Spot availability synced |
+
+### Authority
+- `OnPlayerEntered`/`OnPlayerExited` are called by the server-authoritative `BPC_HidingSystem`.
+- `LockSpot`/`UnlockSpot` are server-only.
+- `GetOccupancyStatus` is read-only, safe for any side.
+
+### Server RPCs
+| RPC | Direction | Description |
+|-----|-----------|-------------|
+| `Server_ClaimSpot` | Client→Server | Client requests occupying spot. Server validates availability. |
+
+---
+
 *Blueprint Spec: Hiding Spot Interface & Actor. Conforms to TEMPLATE.md v1.0 — part of the UE5 Modular Game Framework.*