feat: REV15 audio renderer + HID fix (v0.8.0)

Complete SDK15 audio implementation with native float biquads.
Fixes TotK 1.4.2 and BotW 1.8.2 boot loops.

- Add REV15 float biquad filter support
- Implement VoiceInParameterV2 (0x188 bytes)
- Add SplitterDestinationV2b with biquad filters
- Fix HID sampling number (double state value)
- Add AudioSnoopManager and AudioSystemManager
- Implement FinalOutputRecorder system
- Add FFT and loudness calculator (ITU-R BS.1770)
- Add full Limiter effect

Resolves boot loops and controller detection in SDK20 games.

Signed-off-by: Zephyron <zephyron@citron-emu.org>

src/audio_core/audio_system_manager.cpp

@@ -0,0 +1,128 @@
+// SPDX-FileCopyrightText: Copyright 2025 Citron Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <algorithm>
+
+#include "audio_core/audio_system_manager.h"
+#include "common/logging/log.h"
+#include "core/core.h"
+#include "core/hle/result.h"
+#include "core/hle/service/audio/errors.h"
+
+namespace AudioCore {
+
+AudioSystemManager::AudioSystemManager(Core::System& system_) : system{system_} {}
+AudioSystemManager::~AudioSystemManager() = default;
+
+Result AudioSystemManager::RegisterAppletResourceUserId(u64 applet_resource_user_id) {
+    std::scoped_lock lock{mutex};
+
+    if (registered_count >= MaxAppletResourceUserIds) {
+        LOG_ERROR(Service_Audio, "Maximum applet resource user IDs registered");
+        return Service::Audio::ResultInvalidHandle;
+    }
+
+    // Check if already registered
+    for (size_t i = 0; i < registered_count; i++) {
+        if (registered_ids[i] == applet_resource_user_id) {
+            return ResultSuccess; // Already registered
+        }
+    }
+
+    registered_ids[registered_count++] = applet_resource_user_id;
+    LOG_DEBUG(Service_Audio, "Registered applet resource user ID: {}", applet_resource_user_id);
+    return ResultSuccess;
+}
+
+Result AudioSystemManager::UnregisterAppletResourceUserId(u64 applet_resource_user_id) {
+    std::scoped_lock lock{mutex};
+
+    for (size_t i = 0; i < registered_count; i++) {
+        if (registered_ids[i] == applet_resource_user_id) {
+            // Remove by shifting remaining elements
+            for (size_t j = i; j < registered_count - 1; j++) {
+                registered_ids[j] = registered_ids[j + 1];
+            }
+            registered_count--;
+            LOG_DEBUG(Service_Audio, "Unregistered applet resource user ID: {}",
+                      applet_resource_user_id);
+            return ResultSuccess;
+        }
+    }
+
+    LOG_WARNING(Service_Audio, "Applet resource user ID not found: {}", applet_resource_user_id);
+    return Service::Audio::ResultInvalidHandle;
+}
+
+Result AudioSystemManager::RequestSuspendAudio(u64 applet_resource_user_id) {
+    std::scoped_lock lock{mutex};
+
+    LOG_DEBUG(Service_Audio, "Suspending audio for applet resource user ID: {}",
+              applet_resource_user_id);
+    audio_suspended = true;
+    return ResultSuccess;
+}
+
+Result AudioSystemManager::RequestResumeAudio(u64 applet_resource_user_id) {
+    std::scoped_lock lock{mutex};
+
+    LOG_DEBUG(Service_Audio, "Resuming audio for applet resource user ID: {}",
+              applet_resource_user_id);
+    audio_suspended = false;
+    return ResultSuccess;
+}
+
+Result AudioSystemManager::GetAudioInputProcessMasterVolume(f32& volume) {
+    std::scoped_lock lock{mutex};
+    volume = input_master_volume;
+    return ResultSuccess;
+}
+
+Result AudioSystemManager::SetAudioInputProcessMasterVolume(f32 volume) {
+    std::scoped_lock lock{mutex};
+    input_master_volume = std::clamp(volume, 0.0f, 1.0f);
+    LOG_DEBUG(Service_Audio, "Set audio input master volume: {}", input_master_volume);
+    return ResultSuccess;
+}
+
+Result AudioSystemManager::GetAudioOutputProcessMasterVolume(f32& volume) {
+    std::scoped_lock lock{mutex};
+    volume = output_master_volume;
+    return ResultSuccess;
+}
+
+Result AudioSystemManager::SetAudioOutputProcessMasterVolume(f32 volume) {
+    std::scoped_lock lock{mutex};
+    output_master_volume = std::clamp(volume, 0.0f, 1.0f);
+    LOG_DEBUG(Service_Audio, "Set audio output master volume: {}", output_master_volume);
+    return ResultSuccess;
+}
+
+Result AudioSystemManager::GetAudioOutputProcessRecordVolume(f32& volume) {
+    std::scoped_lock lock{mutex};
+    volume = output_record_volume;
+    return ResultSuccess;
+}
+
+Result AudioSystemManager::SetAudioOutputProcessRecordVolume(f32 volume) {
+    std::scoped_lock lock{mutex};
+    output_record_volume = std::clamp(volume, 0.0f, 1.0f);
+    LOG_DEBUG(Service_Audio, "Set audio output record volume: {}", output_record_volume);
+    return ResultSuccess;
+}
+
+Result AudioSystemManager::RequestSuspendAudioForDebug() {
+    std::scoped_lock lock{mutex};
+    LOG_DEBUG(Service_Audio, "Suspending audio for debug");
+    debug_suspended = true;
+    return ResultSuccess;
+}
+
+Result AudioSystemManager::RequestResumeAudioForDebug() {
+    std::scoped_lock lock{mutex};
+    LOG_DEBUG(Service_Audio, "Resuming audio for debug");
+    debug_suspended = false;
+    return ResultSuccess;
+}
+
+} // namespace AudioCore