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/developer/09-ai-systems.md

@@ -115,4 +115,33 @@
 
 ---
 
+## Multiplayer Networking
+
+### AI is Server-Only
+
+**All AI logic runs on the server.** Behavior trees, perception, memory, and state machines execute on the server only. Clients receive:
+- **Position/Rotation/Animation:** via standard Actor replication
+- **Alert level:** replicated for client awareness UI (detection meter, investigation icon)
+- **Health:** replicated for client health bars
+- **Perception events:** replicated for client awareness indicators only (cosmetic)
+
+### Category Authority Map
+| System | Runs On | Replicated To Clients |
+|--------|---------|----------------------|
+| `AI_BaseAgentController` | Server | Position, rotation, animation |
+| `BP_EnemyBase` | Server | Health, state, mesh |
+| `BPC_AlertSystem` | Server | Alert level enum for UI |
+| `BPC_AIStateMachine` | Server | Current state for animation |
+| `BPC_AIPerceptionSystem` | Server | Detection events → client awareness indicators |
+| `BPC_AIMemorySystem` | Server | LastKnownLocation → client investigation UI |
+| `BPC_BehaviourVariantSelector` | Server (at spawn) | Variant choice for client animation matching |
+| `BP_PatrolPath` | Read-only | Spline data is static; identical on all clients |
+
+### Client Awareness
+- Clients receive perception events (enemy detected player, heard sound) as **cosmetic indicators** — red detection bar, investigation icon, audio cue.
+- The actual AI behavior (investigate, engage, flee) runs on server only.
+- Clients never run behavior trees — they only display the results.
+
+---
+
 *Developer Reference v1.0 — 09 AI Systems. Companion to docs/blueprints/09-ai/ specs.*