MilesLib: run the 40250 sound sources verbatim over an AIL software mixer

Copy SoundBase/SoundData/SoundInstance*/SoundManager*/Type from 40250 and
implement the AIL_* calls they make in MilesAil.cpp (2D pan, 3D distance and
listener pan, threaded stream decode, loop counts). The SDL host drains the
mixer. CSoundManager is created/updated/destroyed where 40250 does it and the
old AudioCommands bridge is removed. Port-map MilesLib 142/142 PORTED.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/port/CMakeLists.txt

@@ -195,6 +195,11 @@ if(BUILD_TESTING AND CMAKE_SYSTEM_NAME STREQUAL CMAKE_HOST_SYSTEM_NAME)
     add_test(NAME port.text COMMAND $<TARGET_FILE:port_text_test>)
     set_tests_properties(port.text PROPERTIES SKIP_RETURN_CODE 77)
 
+    # MilesLib: the 40250 sound managers over the Miles emulation (platform/MilesLib/MilesAil.cpp).
+    add_executable(port_miles_test ${PROJECT_SOURCE_DIR}/tests/port/port_miles_test.cpp)
+    target_link_libraries(port_miles_test PRIVATE port_platform)
+    add_test(NAME port.miles COMMAND $<TARGET_FILE:port_miles_test>)
+
     # 批次 2V1: Packet.h struct sizes against the classic wire layouts.
     add_executable(port_packet_test ${PROJECT_SOURCE_DIR}/tests/port/port_packet_test.cpp
         ${PROJECT_SOURCE_DIR}/tests/port/port_packet_test_wire.cpp)