feat: add inherited sessions and desktop session teardown

kernel/src/Sched/Scheduler.hpp

@@ -86,6 +86,7 @@ namespace Sched {
         char environment[EnvironmentBytes]; // NUL-separated NAME=VALUE entries
         uint32_t environmentLength;
         char user[32];            // Owner user name (inherited from parent on spawn)
+        int sessionId;            // Process-session leader PID (inherited on spawn)
         char cwd[256];            // Absolute current working directory
 
         // Thread-local storage. fsBase is loaded into IA32_FS_BASE when
@@ -252,6 +253,12 @@ namespace Sched {
     // Returns 0 on success, -1 on failure.
     int KillProcess(int pid);
 
+    // Start a new process session for the caller, or terminate every process
+    // belonging to a session. KillSession returns the number of live members
+    // it signalled; callers can repeat until it returns zero.
+    int CreateSession();
+    int KillSession(int sessionId);
+
     // Find a process by PID (returns nullptr if not found or not alive)
     Process* GetProcessByPid(int pid);