addind more important kernel files and also fixing bugs

kernel/shell.c

@@ -0,0 +1,60 @@
+#include "shell.h"
+#include "keyboard.h"
+#include "terminal.h"
+#include <stdio.h>
+#include <string.h>
+
+void execute(char *input) {
+    if (strcmp(input, "help") == 0) {
+        printf("Available commands: help, clear, exit\n");
+    } else if (strcmp(input, "clear") == 0) {
+        terminal_clear();
+    } else {
+        printf("Unknown command: %s\n", input);
+    }
+}
+
+void shell_loop()
+{
+    char input[256];
+    int index = 0;
+    char c;
+
+    while (1)
+    {
+        printf("> ");
+        index = 0;
+
+        while (1)
+        {
+            c = keyboard_get_char(); // Waits for input
+
+            if (c == '\n' || c == '\r')  // Enter key
+            {
+                input[index] = '\0';
+                printf("\n");
+                break;
+            }
+            else if (c == '\b' || c == 127) // Backspace
+            {
+                if (index > 0)
+                {
+                    index--;
+                    printf("\b \b"); // Erase last char on screen
+                }
+            }
+            else
+            {
+                if (index < sizeof(input) - 1) {
+                    input[index++] = c;
+                    putchar(c);
+                }
+            }
+        }
+
+        if (strcmp(input, "exit") == 0)
+            break;
+
+        execute(input);
+    }
+}