ThorVG: Out-of-bounds Read in SFNT/TTF Font Loader via Memory API

Thor Vector Graphics (ThorVG) is a production-ready vector graphics engine. Prior to 1.0.7, the `SFNT/TTF` font loader's `SfntLoader::gen` function in `tvgSfntLoader.cpp` reads `data[0] through data[3]` to identify the font type without first checking that the input buffer contains at least four bytes. Loading an undersized font directly from memory through public APIs such as `tvg::Text::load` causes an out-of-bounds read. Loading through a file path using `mmap` can mask the read because of page alignment; the memory-loading API directly exposes it. Depending on memory layout, a malformed short font may crash the consuming application or disclose adjacent heap memory. This issue is fixed in version 1.0.7.