Bundle ecs-go binaries with ECS, so --turbo works out of the box

[TomasVotruba]

Running vendor/bin/ecs --turbo in a project without ecs-go ended with a bare shell error:

sh: 1: ecs-go: not found

Now the ecs-go binary ships with ECS:

• the release build cross-compiles ecs-go main for linux/darwin × amd64/arm64 into bin/turbo/ (stripped, ~3.7 MB each)
• EcsGoBinaryLocator picks the one matching the current OS and arch, restoring the executable bit if archive extraction dropped it
• lookup order: ECS_TURBO_BIN → bundled → vendor/bin/ecs-go → PATH
• when nothing is found (e.g. Windows - ecs-go does not build there yet, it uses syscall.SYS_IOCTL), --turbo fails with a clear error instead of the shell one