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/11-16-systems.md

@@ -109,3 +109,40 @@
 ---
 
 *Developer Reference v1.0 — Categories 11-16 Systems. Companion to docs/blueprints/ specs.*
+
+---
+
+## Multiplayer Networking
+
+### Category 11-12: Meta & Settings
+| System | Authority |
+|--------|-----------|
+| `BPC_ProgressStatTracker` | Server accumulates; snapshot replicates for scoreboard |
+| `SS_AchievementSystem` | Server validates unlocks; client receives unlock notifications |
+| `BPC_AccessibilitySettings` | **Local per-client** — each player's accessibility preferences |
+| `SS_SettingsSystem` | Settings save per-client; key bindings are local |
+
+### Category 13: Polish
+| System | Authority |
+|--------|-----------|
+| `BPC_AnalyticsTracker` | **Local only** — per-client telemetry |
+| `BPC_DevCheatManager` | **Local only** — but cheats that affect world must be server-validated |
+| `BPC_ErrorHandler` | **Local only** — per-client error handling |
+| `BPC_FPSCounter` | **Local only** — per-client performance |
+| `BPC_LoadingScreen` | **Local only** — but sync'd via GamePhase |
+| `BPC_TutorialSystem` | **Local per-client** — tutorial progression is per-player |
+| `WBP_CreditsScreen`, `WBP_DebugMenu`, `WBP_SplashScreen` | **Local only** |
+
+### Category 14: Data Assets
+All `DA_*` Data Assets are **read-only configuration** — loaded identically on all clients. No replication needed.
+
+### Category 15: Input
+| System | Authority |
+|--------|-----------|
+| `SS_EnhancedInputManager` | **Local per-client.** Input mapping contexts, key rebinding, and input mode are per-player. Context priority stack is per-client. |
+
+### Category 16: State Management
+| System | Authority |
+|--------|-----------|
+| `BPC_StateManager` | **Server-authoritative.** All state change requests go through server. `IsActionPermitted()` is read-only — safe for client prediction. `RequestStateChange()` must be server-validated. |
+| `DA_StateGatingTable` | Read-only Data Asset — identical on all clients. Server uses it for validation; clients use it for prediction of gating results. |