v6.13.1 — stock Lua-CSharp 0.5.6

The bundled Lua VM is now stock Lua-CSharp v0.5.6 instead of a locally patched 0.5.5 build.

• WebGL coroutines work. 0.5.5 posted a suspended coroutine's continuation to the ambient SynchronizationContext — on Unity's main thread that is the very thread parked in GetAwaiter().GetResult(), so a single-threaded WASM player froze on the first coroutine.yield. Fixed upstream as nuskey8/Lua-CSharp#329, for the deadlock reported as #327.
• The local VM patch is retired. #t returning nil under the sandbox's instruction hook — patched into our own Lua.dll since July — landed upstream as #331, so the shipped binary is unmodified upstream again.
• Lua runs ~25% faster (#330): a tight loop 30 ms → 22 ms raw, 165 ms → 127 ms under the sandbox guard.

Drop-in swap: the assembly's public API is identical member-for-member. EditMode: 2538 tests, 2529 passed, 0 failed, 9 skipped.