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>

host/src/audio/audio_overrides.hpp

@@ -0,0 +1,68 @@
+// Per-game audio-format overrides, persisted next to the exe so a game whose hooked
+// format was wrong/unrecoverable is auto-corrected on its next launch. Keyed by the
+// game's image name (case-insensitive). Two writers: the operator's manual Override, and
+// auto-learning a format the hook caught exactly at IAudioClient::Initialize (ground
+// truth). A human-readable one-line-per-game text file:
+//
+//   # CoopAllTheThings per-game audio overrides
+//   brotato.exe = 44100 2 32 float
+//   snb.exe = 48000 2 16 pcm
+#pragma once
+
+#include <cstdint>
+#include <map>
+#include <string>
+
+namespace coop
+{
+
+struct AudioFormatOverride
+{
+	std::uint32_t rate = 0;
+	std::uint32_t channels = 0;
+	std::uint32_t bits = 0;
+	std::uint32_t format_tag = 0; // WAVE_FORMAT_PCM (1) / WAVE_FORMAT_IEEE_FLOAT (3)
+
+	[[nodiscard]] bool valid() const
+	{
+		return rate != 0 && channels != 0 && bits != 0;
+	}
+	bool operator==(const AudioFormatOverride& o) const
+	{
+		return rate == o.rate && channels == o.channels && bits == o.bits && format_tag == o.format_tag;
+	}
+	bool operator!=(const AudioFormatOverride& o) const
+	{
+		return !(*this == o);
+	}
+};
+
+class AudioOverrideStore
+{
+public:
+	// `path` empty -> default (exe_dir/coop_audio_overrides.ini). Does not load yet.
+	explicit AudioOverrideStore(std::wstring path = {});
+
+	void load(); // (re)read the file; missing file is fine (empty store)
+
+	// Look up an override by image name (case-insensitive, basename). False if none.
+	[[nodiscard]] bool find(const std::wstring& image_name, AudioFormatOverride& out) const;
+
+	// Store image_name -> fmt and persist immediately. Sets *differed = true when an
+	// existing entry for that game differed from `fmt` (caller warns the operator).
+	void set(const std::wstring& image_name, const AudioFormatOverride& fmt, bool* differed = nullptr);
+
+	[[nodiscard]] const std::wstring& path() const
+	{
+		return path_;
+	}
+
+private:
+	static std::wstring key_of(const std::wstring& image_name); // lowercased basename
+	void save() const;
+
+	std::wstring path_;
+	std::map<std::wstring, AudioFormatOverride> map_;
+};
+
+} // namespace coop