The web build could only open local/uploaded files after launch, which made forum/shared .slvs links cumbersome to inspect. This change adds launch-time URL ingestion so the app can start directly with a remote file.

• Startup URL parameter handling

  • src/platform/guihtml.cpp now reads window.location.search for url or file.
  • This is wired into Platform::InitGui(...), so it plugs into the existing startup file-open path (no new load flow).

• Remote file staging into Emscripten FS

  • If a launch URL is provided and no CLI file arg is already present, the file is fetched via emscripten_fetch.
  • The fetched bytes are written to /data/<filename> and that path is appended to startup args, allowing normal SS.Load(...) behavior.

• Path/filename hardening and portability

  • Filename derivation from URL pathname is constrained (rejects unsafe names like ./.. and path separators).
  • Logging and byte-count checks were tightened for cross-platform correctness (PRIu64, safe type comparison).

// Launch URL support in InitGui():
std::string launchFileUrl = GetLaunchFileUrl();
if(args.size() < 2 && !launchFileUrl.empty()) {
    std::string launchFileName = GetFilenameFromUrl(launchFileUrl);
    std::string launchFilePath = Path::From(basePathInFilesystem).Join(launchFileName).raw;
    if(DownloadFileToFilesystem(launchFileUrl, launchFilePath)) {
        args.push_back(launchFilePath);
    }
}