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.h

@@ -0,0 +1,137 @@
+// SPDX-FileCopyrightText: Copyright 2025 Citron Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <array>
+#include <mutex>
+
+#include "common/common_types.h"
+#include "core/hle/result.h"
+
+namespace Core {
+class System;
+}
+
+namespace AudioCore {
+
+/**
+ * Manages audio system state for applets including suspend/resume and volume control.
+ */
+class AudioSystemManager {
+public:
+    explicit AudioSystemManager(Core::System& system);
+    ~AudioSystemManager();
+
+    /**
+     * Register an applet resource user ID.
+     *
+     * @param applet_resource_user_id - Applet resource user ID to register.
+     * @return Result code.
+     */
+    Result RegisterAppletResourceUserId(u64 applet_resource_user_id);
+
+    /**
+     * Unregister an applet resource user ID.
+     *
+     * @param applet_resource_user_id - Applet resource user ID to unregister.
+     * @return Result code.
+     */
+    Result UnregisterAppletResourceUserId(u64 applet_resource_user_id);
+
+    /**
+     * Request audio suspension.
+     *
+     * @param applet_resource_user_id - Applet resource user ID.
+     * @return Result code.
+     */
+    Result RequestSuspendAudio(u64 applet_resource_user_id);
+
+    /**
+     * Request audio resumption.
+     *
+     * @param applet_resource_user_id - Applet resource user ID.
+     * @return Result code.
+     */
+    Result RequestResumeAudio(u64 applet_resource_user_id);
+
+    /**
+     * Get audio input process master volume.
+     *
+     * @param volume - Output volume value.
+     * @return Result code.
+     */
+    Result GetAudioInputProcessMasterVolume(f32& volume);
+
+    /**
+     * Set audio input process master volume.
+     *
+     * @param volume - Volume value to set.
+     * @return Result code.
+     */
+    Result SetAudioInputProcessMasterVolume(f32 volume);
+
+    /**
+     * Get audio output process master volume.
+     *
+     * @param volume - Output volume value.
+     * @return Result code.
+     */
+    Result GetAudioOutputProcessMasterVolume(f32& volume);
+
+    /**
+     * Set audio output process master volume.
+     *
+     * @param volume - Volume value to set.
+     * @return Result code.
+     */
+    Result SetAudioOutputProcessMasterVolume(f32 volume);
+
+    /**
+     * Get audio output process record volume.
+     *
+     * @param volume - Output volume value.
+     * @return Result code.
+     */
+    Result GetAudioOutputProcessRecordVolume(f32& volume);
+
+    /**
+     * Set audio output process record volume.
+     *
+     * @param volume - Volume value to set.
+     * @return Result code.
+     */
+    Result SetAudioOutputProcessRecordVolume(f32 volume);
+
+    /**
+     * Request audio suspension for debugging.
+     *
+     * @return Result code.
+     */
+    Result RequestSuspendAudioForDebug();
+
+    /**
+     * Request audio resumption for debugging.
+     *
+     * @return Result code.
+     */
+    Result RequestResumeAudioForDebug();
+
+private:
+    static constexpr size_t MaxAppletResourceUserIds = 8;
+
+    Core::System& system;
+    std::mutex mutex;
+
+    std::array<u64, MaxAppletResourceUserIds> registered_ids{};
+    size_t registered_count{0};
+
+    f32 input_master_volume{1.0f};
+    f32 output_master_volume{1.0f};
+    f32 output_record_volume{1.0f};
+
+    bool audio_suspended{false};
+    bool debug_suspended{false};
+};
+
+} // namespace AudioCore