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>

Tools/pack_z_asset.sh

@@ -0,0 +1,79 @@
+#!/usr/bin/env bash
+# RR3 Asset Packer - Cross-Platform
+# Compresses files with ZLIB to create .z format
+
+set -euo pipefail
+
+# Colors
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+CYAN='\033[0;36m'
+NC='\033[0m'
+
+echo -e "${CYAN}════════════════════════════════════════════════════════════${NC}"
+echo -e "${YELLOW}   RR3 Asset Packer - Linux/Unix${NC}"
+echo -e "${CYAN}════════════════════════════════════════════════════════════${NC}"
+echo ""
+
+# Check Python 3
+if ! command -v python3 &> /dev/null; then
+    echo -e "${RED}ERROR: Python 3 is not installed!${NC}"
+    exit 1
+fi
+
+# Check arguments
+if [ "$#" -lt 1 ]; then
+    echo "Usage: $0 <input_file>"
+    echo ""
+    echo "Example:"
+    echo "  $0 sprites_0.etc.dds"
+    echo ""
+    echo "Output will be: input_file.z"
+    exit 1
+fi
+
+INPUT_FILE="$1"
+
+if [ ! -f "$INPUT_FILE" ]; then
+    echo -e "${RED}ERROR: Input file not found: $INPUT_FILE${NC}"
+    exit 1
+fi
+
+OUTPUT_FILE="${INPUT_FILE}.z"
+
+echo -e "${GREEN}Input:${NC}  $INPUT_FILE"
+echo -e "${GREEN}Output:${NC} $OUTPUT_FILE"
+echo ""
+
+# Pack with Python
+python3 - "$INPUT_FILE" "$OUTPUT_FILE" << 'PYTHON_SCRIPT'
+import sys
+import zlib
+import os
+
+input_file = sys.argv[1]
+output_file = sys.argv[2]
+
+print("Reading file...")
+with open(input_file, "rb") as f:
+    data = f.read()
+
+print(f"Input size: {len(data):,} bytes")
+
+print("Compressing with ZLIB (level 9)...")
+compressed = zlib.compress(data, level=9)
+
+print(f"Compressed size: {len(compressed):,} bytes")
+print(f"Compression ratio: {(1 - len(compressed) / len(data)) * 100:.1f}%")
+
+print("Writing output...")
+with open(output_file, "wb") as f:
+    f.write(compressed)
+
+print("")
+print("✅ Packing complete!")
+PYTHON_SCRIPT
+
+echo ""
+echo -e "${GREEN}Done!${NC}"