Add embedded assets, splash screens, and asset loading support

Features added:
- Embedded main.lua and Lua files support (EMBED_MAIN option)
- Embedded assets support (EMBED_ASSETS option)
- Splash screens with dual logo display (always embedded)
- Asset loading progress tracking API (BeginAssetLoading, UpdateAssetLoading, EndAssetLoading)
- Custom font embedding for splash/loading screens
- --log flag for Windows console control
- --no-logo flag to skip splash screens in development
- Python scripts for embedding (embed_lua.py, embed_assets.py, embed_logo.py, embed_font.py)
- Documentation (EMBEDDING.md, ASSET_LOADING.md, SPLASH_SCREENS.md)

This allows building single-executable releases with all Lua code and assets embedded.

embed_lua.py

@@ -0,0 +1,92 @@
+#!/usr/bin/env python3
+"""
+Embed multiple Lua files into a C header file for inclusion in the executable.
+Usage: python embed_lua.py <output.h> <file1.lua> [file2.lua] [file3.lua] ...
+
+Embeds all specified Lua files into a C header with a virtual filesystem.
+The first file is treated as main.lua (entry point).
+"""
+import sys
+import os
+
+def sanitize_name(filename):
+    """Convert filename to valid C identifier"""
+    name = os.path.basename(filename)
+    name = name.replace('.', '_').replace('-', '_').replace('/', '_').replace('\\', '_')
+    return name
+
+def embed_files(output_file, input_files):
+    with open(output_file, 'w') as f:
+        f.write('#ifndef EMBEDDED_MAIN_H\n')
+        f.write('#define EMBEDDED_MAIN_H\n\n')
+        f.write('/* Auto-generated file - do not edit manually */\n\n')
+        
+        # Embed each file as a separate array
+        for idx, input_file in enumerate(input_files):
+            with open(input_file, 'rb') as inf:
+                data = inf.read()
+            
+            var_name = sanitize_name(input_file)
+            f.write(f'/* Embedded file: {input_file} */\n')
+            f.write(f'static const unsigned char embedded_lua_{idx}_{var_name}[] = {{\n')
+            
+            for i, byte in enumerate(data):
+                if i % 12 == 0:
+                    f.write('    ')
+                f.write(f'0x{byte:02x}')
+                if i < len(data) - 1:
+                    f.write(',')
+                    if (i + 1) % 12 == 0:
+                        f.write('\n')
+                    else:
+                        f.write(' ')
+            
+            f.write('\n};\n')
+            f.write(f'static const unsigned int embedded_lua_{idx}_{var_name}_len = {len(data)};\n\n')
+        
+        # Create the file table
+        f.write('/* File table for virtual filesystem */\n')
+        f.write('typedef struct {\n')
+        f.write('    const char* name;\n')
+        f.write('    const unsigned char* data;\n')
+        f.write('    unsigned int size;\n')
+        f.write('} EmbeddedLuaFile;\n\n')
+        
+        f.write('static const EmbeddedLuaFile embedded_lua_files[] = {\n')
+        for idx, input_file in enumerate(input_files):
+            var_name = sanitize_name(input_file)
+            # Store both original filename and basename for require compatibility
+            basename = os.path.basename(input_file)
+            f.write(f'    {{ "{basename}", embedded_lua_{idx}_{var_name}, embedded_lua_{idx}_{var_name}_len }},\n')
+        f.write('};\n\n')
+        
+        f.write(f'static const int embedded_lua_file_count = {len(input_files)};\n\n')
+        
+        # Main entry point (first file)
+        var_name = sanitize_name(input_files[0])
+        f.write('/* Main entry point */\n')
+        f.write(f'#define embedded_main_lua embedded_lua_0_{var_name}\n')
+        f.write(f'#define embedded_main_lua_len embedded_lua_0_{var_name}_len\n\n')
+        
+        f.write('#endif /* EMBEDDED_MAIN_H */\n')
+
+if __name__ == '__main__':
+    if len(sys.argv) < 3:
+        print('Usage: python embed_lua.py <output.h> <file1.lua> [file2.lua] ...')
+        print('  The first Lua file is treated as the main entry point.')
+        sys.exit(1)
+    
+    output_file = sys.argv[1]
+    input_files = sys.argv[2:]
+    
+    # Check all input files exist
+    for f in input_files:
+        if not os.path.exists(f):
+            print(f'Error: File not found: {f}')
+            sys.exit(1)
+    
+    embed_files(output_file, input_files)
+    print(f'Embedded {len(input_files)} file(s) into {output_file}')
+    for f in input_files:
+        print(f'  - {f}')
+