changed from angle brackets to quotes for gem-local HAL headers
(task.h, io_hal.h, socket_hal.h), and removed relative path prefix
from task.h include. this follows the mrbgem build system convention
where gem/include/ is automatically added to the include path.
Co-authored-by: Claude <noreply@anthropic.com>
separate platform-specific socket operations into HAL implementations
for POSIX (Linux/macOS/BSD/Unix) and Windows platforms to improve
portability and maintainability
Co-authored-by: Claude <noreply@anthropic.com>