Link tasks to address spaces

Extends TCB with an address space pointer to enable per-task memory
isolation. Each task can now reference its own memory protection
domain through the flex page mechanism.

Author: HeatCrab

include/sys/task.h

@@ -59,6 +59,9 @@ enum task_states {
 #define TASK_TIMESLICE_LOW 10     /* Low priority: longer slice */
 #define TASK_TIMESLICE_IDLE 15    /* Idle tasks: longest slice */
 
+/* Forward declaration */
+struct as;
+
 /* Task Control Block (TCB)
  *
  * Contains all essential information about a single task, including saved
@@ -71,6 +74,9 @@ typedef struct tcb {
     size_t stack_sz; /* Total size of the stack in bytes */
     void (*entry)(void); /* Task's entry point function */
 
+    /* Memory Protection */
+    struct as *as_ptr; /* Address space for memory isolation */
+
     /* Scheduling Parameters */
     uint16_t prio;      /* Encoded priority (base and time slice counter) */
     uint8_t prio_level; /* Priority level (0-7, 0 = highest) */