Audio: per-game persisted format overrides + auto-learn

Persist audio overrides keyed by game image name (coop_audio_overrides.ini
next to the exe) so a known-bad game is auto-corrected on its next launch:
on attach to a guessed stream the host applies any saved override, and a
manual Override now saves too. A format the hook catches exactly at
IAudioClient::Initialize is auto-saved as that game's override (ground truth);
if it overwrites a differing stored value, a warning is logged. Host-originated
log lines now reach the Log window via IpcServer::host_log (color-coded).

Validated live (harness): a pre-seeded override for coop_tone is auto-applied
over the guess (state -> manual override, 48000/2/16). audio_overrides_test
covers persist/reload/case-insensitive lookup/differing-overwrite. Trim README.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/CMakeLists.txt

@@ -36,6 +36,15 @@ add_executable(rate_estimator_test rate_estimator_test.cpp)
 target_include_directories(rate_estimator_test PRIVATE ${CMAKE_SOURCE_DIR}/hook/src)
 add_test(NAME rate_estimator_test COMMAND rate_estimator_test)
 
+# Unit test for the per-game audio override store (persist/reload, case-insensitive
+# lookup, differing-overwrite detection). Reuses the shipping source. No device.
+add_executable(audio_overrides_test
+	audio_overrides_test.cpp
+	${CMAKE_SOURCE_DIR}/host/src/audio/audio_overrides.cpp)
+target_include_directories(audio_overrides_test PRIVATE ${CMAKE_SOURCE_DIR}/host/src)
+target_link_libraries(audio_overrides_test PRIVATE coop_common)
+add_test(NAME audio_overrides_test COMMAND audio_overrides_test)
+
 # Unit test for the host->game mouse coordinate mapping (letterbox inverse +
 # decorated-window client offset). Header-only, no device.
 add_executable(mkb_map_test mkb_map_test.cpp)
@@ -163,6 +172,7 @@ coop_output_subdir(tests
 	mkb_map_test
 	audio_mix_test
 	rate_estimator_test
+	audio_overrides_test
 	audio_loopback_test
 	audio_hook_test
 	srgb_format_test