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/02-player/15_BPC_PlayerMetricsTracker.md

@@ -332,4 +332,26 @@ flowchart TD
 
 ---
 
+## 11. Multiplayer Networking
+
+### Replication
+| Variable | Condition | Purpose |
+|----------|-----------|---------|
+| `CurrentSnapshot` | `Replicated` | Synced for scoreboard, playstyle classification |
+
+### Authority
+- **Server** accumulates all metrics (listens to gameplay dispatchers server-side).
+- **Server** creates periodic snapshots and replicates.
+- **Clients** only read metrics (for local HUD/scoreboard display).
+
+### Server RPCs
+| RPC | Direction | Description |
+|-----|-----------|-------------|
+| `Server_LogEvent` | Client→Server | Client reports a metric event. Server validates before recording. |
+
+### Anti-Cheat
+- Server validates `Server_LogEvent` calls: damage dealt must match server calculations, distance traveled must be plausible, item pickups validated by inventory system.
+
+---
+
 *Blueprint Spec: Player Metrics Tracker. Conforms to TEMPLATE.md v1.0 — part of the UE5 Modular Game Framework.*