fix: various fixes

kernel/src/Api/Syscall.hpp

@@ -83,6 +83,9 @@ namespace Zenith {
     static constexpr uint64_t SYS_KILL        = 62;
     static constexpr uint64_t SYS_DEVLIST     = 63;
 
+    // Kernel introspection syscalls
+    static constexpr uint64_t SYS_MEMSTATS    = 67;
+
     static constexpr int SOCK_TCP = 1;
     static constexpr int SOCK_UDP = 2;
 
@@ -162,6 +165,13 @@ namespace Zenith {
         uint64_t pixelVa;  // VA of pixel buffer in caller's address space
     };
 
+    struct MemStats {
+        uint64_t totalBytes;
+        uint64_t freeBytes;
+        uint64_t usedBytes;
+        uint64_t pageSize;
+    };
+
     struct DevInfo {
         uint8_t  category;     // 0=CPU, 1=Interrupt, 2=Timer, 3=Input, 4=USB, 5=Network, 6=Display, 7=PCI
         uint8_t  _pad[3];