feat: audio mixer, Audio app, fix Installer crash

kernel/src/Sched/Scheduler.cpp

@@ -21,6 +21,7 @@
 #include <Api/WinServer.hpp>
 #include <Api/Heap.hpp>
 #include <Api/LibSyscall.hpp>
+#include <Drivers/Audio/Mixer.hpp>
 #include <Ipc/Ipc.hpp>
 
 // Assembly: context switch with CR3 and FPU state parameters
@@ -715,6 +716,10 @@ namespace Sched {
         // Clean up any windows owned by this process
         WinServer::CleanupProcess(exitingPid);
 
+        // Release any mixer virtual streams owned by this process so the slot
+        // and its ring buffer don't leak when an app forgets to audio_close.
+        Drivers::Audio::Mixer::CleanupProcess(exitingPid);
+
         // Release process-scoped IPC handles/mappings before tearing down the address space.
         Ipc::CleanupProcessSlot(slot, exitingPid, proc.pml4Phys);
         Montauk::CleanupHeapForSlot(slot, proc.pml4Phys);
@@ -873,6 +878,7 @@ namespace Sched {
 
         // Safe to clean up resources now -- process is not running anywhere.
         WinServer::CleanupProcess(killedPid);
+        Drivers::Audio::Mixer::CleanupProcess(killedPid);
         Ipc::CleanupProcessSlot(slot, killedPid, proc.pml4Phys);
         Montauk::CleanupHeapForSlot(slot, proc.pml4Phys);
         Montauk::CleanupLibTable(slot);