Replace MPQ runtime with loose file asset system

Extract assets from MPQ archives into organized loose files indexed by
manifest.json, enabling fully parallel reads without StormLib serialization.
Add asset_extract and blp_convert tools, PNG texture override support.

tools/asset_extract/manifest_writer.cpp

@@ -0,0 +1,67 @@
+#include "manifest_writer.hpp"
+#include <fstream>
+#include <sstream>
+#include <iomanip>
+#include <zlib.h>
+
+namespace wowee {
+namespace tools {
+
+uint32_t ManifestWriter::computeCRC32(const uint8_t* data, size_t size) {
+    return static_cast<uint32_t>(::crc32(::crc32(0L, Z_NULL, 0), data, static_cast<uInt>(size)));
+}
+
+bool ManifestWriter::write(const std::string& outputPath,
+                           const std::string& basePath,
+                           const std::vector<FileEntry>& entries) {
+    // Write JSON manually to avoid pulling nlohmann/json into the tool
+    // (though it would also work fine). This keeps the tool dependency-light.
+    std::ofstream file(outputPath);
+    if (!file.is_open()) {
+        return false;
+    }
+
+    file << "{\n";
+    file << "  \"version\": 1,\n";
+    file << "  \"basePath\": \"" << basePath << "\",\n";
+    file << "  \"fileCount\": " << entries.size() << ",\n";
+    file << "  \"entries\": {\n";
+
+    for (size_t i = 0; i < entries.size(); ++i) {
+        const auto& e = entries[i];
+
+        // Escape backslashes in WoW path for JSON
+        std::string escapedKey;
+        for (char c : e.wowPath) {
+            if (c == '\\') escapedKey += "\\\\";
+            else if (c == '"') escapedKey += "\\\"";
+            else escapedKey += c;
+        }
+
+        std::string escapedPath;
+        for (char c : e.filesystemPath) {
+            if (c == '\\') escapedPath += "\\\\";
+            else if (c == '"') escapedPath += "\\\"";
+            else escapedPath += c;
+        }
+
+        // CRC32 as hex
+        std::ostringstream hexCrc;
+        hexCrc << std::hex << std::setfill('0') << std::setw(8) << e.crc32;
+
+        file << "    \"" << escapedKey << "\": {\"p\": \"" << escapedPath
+             << "\", \"s\": " << e.size
+             << ", \"h\": \"" << hexCrc.str() << "\"}";
+
+        if (i + 1 < entries.size()) file << ",";
+        file << "\n";
+    }
+
+    file << "  }\n";
+    file << "}\n";
+
+    return file.good();
+}
+
+} // namespace tools
+} // namespace wowee