[jschueller]

Critical:

• Fix use-after-free in mupRelease by deleting outside MU_TRY/MU_CATCH

High:

• Add missing MU_TRY/MU_CATCH to mupDefineNameChars, mupDefineOprtChars, mupDefineInfixOprtChars to prevent exceptions crossing C ABI boundary
• Make s_tmpOutBuf, mupGetVar, mupGetExprVar, mupGetConst buffers thread_local to fix data races in multi-threaded usage
• Fix IsVal returning 0 for all-digit strings (npos not handled)
• Fix IsHexVal returning success when no hex digits follow "0x"
• Add null pointer checks for variable pointers in ParseCmdCodeShort

Medium:

• Fix AsciiDump bounds check to validate string buffer index, not bytecode loop index
• Skip constant folding when divisor is zero instead of producing inf
• Add INT_MIN / -1 overflow check in Div and Mod (undefined behavior)
• Cast to unsigned before shifting in Shr/Shl to avoid UB on negatives
• Check stIf/stElse non-empty before top() in Finalize to prevent crash on malformed bytecode

Low:

• Remove unused global variable g_nBulkSize
• Fix exception safety in ParserCallback::Assign by creating new object before deleting old one