Add RR3 Asset Extraction & Management System

Cross-Platform Scripts:
- extract_z_asset.sh: Linux/Unix single file extraction
- batch_extract_z_assets.sh: Linux/Unix batch extraction
- pack_z_asset.sh: Linux/Unix asset packing
- extract_z_asset.ps1: Windows PowerShell extraction

Server Integration:
- AssetExtractionService.cs: C# service for ZLIB extraction/packing
- AssetManagementController.cs: API endpoints for asset management
  - POST /api/AssetManagement/extract
  - POST /api/AssetManagement/pack
  - POST /api/AssetManagement/batch-extract
  - GET /api/AssetManagement/list
- Registered AssetExtractionService in Program.cs

Features:
- Extracts .z files (ZLIB compressed textures/data)
- Packs files to .z format with ZLIB compression
- Batch processing support
- Cross-platform (Windows/Linux/macOS)
- Server-side API for remote asset management
- Path traversal protection

Documentation:
- ASSET_EXTRACTION_GUIDE.md: Complete integration guide
- Tools/README.md: CLI tool documentation

Based on: Tankonline/Real-Racing-3-Texture-Extraction-Tool
Converted to cross-platform bash/PowerShell scripts + C# service

Ready for .pak asset extraction when files arrive from community

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

RR3CommunityServer/bin/Release/net8.0/appsettings.json

@@ -0,0 +1,22 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  },
+  "AllowedHosts": "*",
+  "AssetsBasePath": "Assets/downloaded",
+  "CustomAssetsPath": "Assets/custom",
+  "ModsPath": "Assets/mods",
+  "ServerSettings": {
+    "AllowSelfSignedCerts": true,
+    "EnableAssetDownloads": true,
+    "FreeGoldPurchases": true,
+    "UnlockAllCars": false,
+    "UnlimitedCurrency": false,
+    "EnableModding": true,
+    "MaxCustomCarUploadSizeMB": 100,
+    "MaxCustomTrackUploadSizeMB": 200
+  }
+}