feat: add SYS_GETCAPS syscall to retrieve process capabilities

kernel/src/Api/Syscall.hpp

@@ -346,6 +346,9 @@ namespace montauk::abi {
     /* Battery.hpp -- ACPI battery status */
     static constexpr uint64_t SYS_BATTERYINFO          = 188;  // (BatteryInfo*) -> 0, -1 no battery device
 
+    /* Process.hpp -- the caller's own capability masks. */
+    static constexpr uint64_t SYS_GETCAPS              = 189;  // (SpawnCapabilities*) -> 0, -1 bad pointer
+
     /* Kernel-owned process capabilities. User identities may namespace
        per-user resources, but never participate in authorization decisions. */
     static constexpr uint64_t CAP_PROCESS_ADMIN = 1ULL << 0;