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/batch_extract_z_assets.sh

@@ -0,0 +1,136 @@
+#!/usr/bin/env bash
+# RR3 Batch Asset Extraction - Cross-Platform
+# Extracts multiple .z files from a directory
+
+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 "${YELLOW}   RR3 Batch Asset Extraction - Linux/Unix${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_directory> [output_directory]"
+    echo ""
+    echo "Example:"
+    echo "  $0 /path/to/rr3/assets"
+    echo "  $0 /path/to/rr3/assets /path/to/output"
+    exit 1
+fi
+
+INPUT_DIR="$1"
+OUTPUT_DIR="${2:-$INPUT_DIR/extracted}"
+
+if [ ! -d "$INPUT_DIR" ]; then
+    echo -e "${RED}ERROR: Input directory not found: $INPUT_DIR${NC}"
+    exit 1
+fi
+
+echo -e "${GREEN}Input directory:${NC} $INPUT_DIR"
+echo -e "${GREEN}Output directory:${NC} $OUTPUT_DIR"
+echo ""
+
+# Create output directory
+mkdir -p "$OUTPUT_DIR"
+
+# Find all .z files
+echo "Scanning for .z files..."
+Z_FILES=($(find "$INPUT_DIR" -type f -name "*.z"))
+
+if [ ${#Z_FILES[@]} -eq 0 ]; then
+    echo -e "${RED}ERROR: No .z files found in $INPUT_DIR${NC}"
+    exit 1
+fi
+
+echo -e "${GREEN}Found ${#Z_FILES[@]} .z files${NC}"
+echo ""
+
+# Process each file
+COUNT=0
+SUCCESS=0
+FAILED=0
+
+for Z_FILE in "${Z_FILES[@]}"; do
+    COUNT=$((COUNT + 1))
+    echo -e "${CYAN}[${COUNT}/${#Z_FILES[@]}] Processing: $(basename "$Z_FILE")${NC}"
+    
+    if python3 - "$Z_FILE" "$OUTPUT_DIR" << 'PYTHON_SCRIPT'
+import sys
+import os
+import zlib
+
+def extract(input_file, output_dir):
+    with open(input_file, "rb") as f:
+        data = f.read()
+    
+    out = b""
+    i = 0
+    found = 0
+    
+    while i < len(data) - 2:
+        if data[i] == 0x78 and data[i+1] in (0x9C, 0xDA, 0x01):
+            try:
+                d = zlib.decompress(data[i:])
+                out += d
+                found += 1
+                i += len(d)
+                continue
+            except:
+                pass
+        i += 1
+    
+    if found == 0:
+        return False
+    
+    base = os.path.basename(input_file)
+    if base.lower().endswith(".z"):
+        base = base[:-2]
+    
+    output_file = os.path.join(output_dir, base)
+    
+    with open(output_file, "wb") as f:
+        f.write(out)
+    
+    print(f"  ✅ Extracted: {base} ({found} blocks, {len(out):,} bytes)")
+    return True
+
+try:
+    if extract(sys.argv[1], sys.argv[2]):
+        sys.exit(0)
+    else:
+        print("  ❌ No ZLIB blocks found")
+        sys.exit(1)
+except Exception as e:
+    print(f"  ❌ Error: {e}")
+    sys.exit(1)
+PYTHON_SCRIPT
+    then
+        SUCCESS=$((SUCCESS + 1))
+    else
+        FAILED=$((FAILED + 1))
+    fi
+    echo ""
+done
+
+echo -e "${CYAN}════════════════════════════════════════════════════════════${NC}"
+echo -e "${GREEN}Batch extraction complete!${NC}"
+echo -e "  Total files: ${#Z_FILES[@]}"
+echo -e "  ${GREEN}Success: $SUCCESS${NC}"
+if [ $FAILED -gt 0 ]; then
+    echo -e "  ${RED}Failed: $FAILED${NC}"
+fi
+echo -e "${CYAN}════════════════════════════════════════════════════════════${NC}"