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/extract_z_asset.sh

@@ -0,0 +1,123 @@
+#!/usr/bin/env bash
+# RR3 Asset Extraction Script - Cross-Platform
+# Extracts .z (ZLIB compressed) texture files from Real Racing 3
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+ROOT_DIR="$(dirname "$SCRIPT_DIR")"
+
+# Colors
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+CYAN='\033[0;36m'
+NC='\033[0m' # No Color
+
+echo -e "${CYAN}════════════════════════════════════════════════════════════${NC}"
+echo -e "${YELLOW}   RR3 Asset Extraction Tool - Linux/Unix${NC}"
+echo -e "${CYAN}════════════════════════════════════════════════════════════${NC}"
+echo ""
+
+# Check if Python 3 is installed
+if ! command -v python3 &> /dev/null; then
+    echo -e "${RED}ERROR: Python 3 is not installed!${NC}"
+    echo "Please install Python 3 to continue."
+    exit 1
+fi
+
+# Check arguments
+if [ "$#" -lt 1 ]; then
+    echo "Usage: $0 <input.z> [output_folder]"
+    echo ""
+    echo "Examples:"
+    echo "  $0 sprites_0.etc.dds.z"
+    echo "  $0 sprites_0.etc.dds.z /path/to/output"
+    exit 1
+fi
+
+INPUT_FILE="$1"
+OUTPUT_DIR="${2:-$(dirname "$INPUT_FILE")}"
+
+# Validate input file
+if [ ! -f "$INPUT_FILE" ]; then
+    echo -e "${RED}ERROR: Input file not found: $INPUT_FILE${NC}"
+    exit 1
+fi
+
+echo -e "${GREEN}Input file:${NC} $INPUT_FILE"
+echo -e "${GREEN}Output directory:${NC} $OUTPUT_DIR"
+echo ""
+
+# Create output directory if it doesn't exist
+mkdir -p "$OUTPUT_DIR"
+
+# Extract using Python
+python3 - "$INPUT_FILE" "$OUTPUT_DIR" << 'PYTHON_SCRIPT'
+import sys
+import os
+import zlib
+
+def main():
+    input_file = sys.argv[1]
+    output_dir = sys.argv[2]
+    
+    print("Reading file...")
+    
+    with open(input_file, "rb") as f:
+        data = f.read()
+    
+    out = b""
+    i = 0
+    found = 0
+    
+    print("Scanning for ZLIB blocks...")
+    
+    # Scan for zlib blocks
+    while i < len(data) - 2:
+        if data[i] == 0x78 and data[i+1] in (0x9C, 0xDA, 0x01):
+            try:
+                d = zlib.decompress(data[i:])
+                out += d
+                print(f"  [+] Block {found} at {hex(i)}")
+                found += 1
+                i += len(d)
+                continue
+            except:
+                pass
+        i += 1
+    
+    if found == 0:
+        print("ERROR: No valid zlib blocks found!")
+        sys.exit(1)
+    
+    # Get output filename
+    base = os.path.basename(input_file)
+    if base.lower().endswith(".z"):
+        base = base[:-2]
+    
+    output_file = os.path.join(output_dir, base)
+    
+    # Backup if exists
+    if os.path.exists(output_file):
+        bak = output_file + ".bak"
+        if not os.path.exists(bak):
+            os.rename(output_file, bak)
+            print(f"Backup created: {bak}")
+    
+    # Write file
+    with open(output_file, "wb") as f:
+        f.write(out)
+    
+    print("")
+    print(f"✅ Extraction complete!")
+    print(f"Output: {output_file}")
+    print(f"Blocks found: {found}")
+    print(f"Size: {len(out):,} bytes")
+
+if __name__ == "__main__":
+    main()
+PYTHON_SCRIPT
+
+echo ""
+echo -e "${GREEN}Done!${NC}"