implemented quick sort, ported the repl to run on the ct vm and added some more optimizations

tests/quick_sort.expected

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tests/quick_sort.sl

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+import ../stdlib/stdlib.sl
+import ../stdlib/io.sl
+import ../stdlib/arr.sl
+
+# Get element from static array, preserving the array pointer
+# [*, arr | i] -> [*, arr | value]
+word aget
+    over swap arr_get_static
+end
+
+# Set element in static array, preserving the array pointer
+# [*, arr, value | i] -> [* | arr]
+word aset
+    rot dup >r -rot arr_set_static r>
+end
+
+# Swap elements at indices i and j in a static array
+# [*, arr, i | j] -> [* | arr]
+word arr_swap
+    >r >r
+    0 rpick aget
+    swap
+    1 rpick aget
+    0 rpick aset
+    swap
+    1 rpick aset
+    rdrop rdrop
+end
+
+# Lomuto partition (ascending, signed comparison)
+# [*, arr, lo | hi] -> [*, arr | pivot_index]
+word partition
+    >r >r
+    1 rpick aget
+    >r
+    1 rpick dec
+    1 rpick
+    while dup 2 rpick < do
+        2 pick over aget nip
+        0 rpick <=
+        if
+            swap inc swap
+            2 pick 2 pick 2 pick arr_swap drop
+        end
+        inc
+    end
+    drop inc
+    over over 2 rpick arr_swap drop
+    rdrop rdrop rdrop
+end
+
+# Recursive quicksort
+# [*, arr, lo | hi] -> [* | arr]
+word qsort_rec
+    over over >= if
+        drop drop
+    else
+        >r >r
+        0 rpick 1 rpick
+        partition
+        over 0 rpick
+        2 pick dec
+        qsort_rec
+        drop
+        over swap inc
+        1 rpick
+        qsort_rec
+        drop
+        rdrop rdrop
+    end
+end
+
+# Quicksort for static arrays (in-place, ascending)
+# [* | arr] -> [* | arr]
+word arr_qsort
+    dup @ dec
+    dup 0 < if
+        drop
+    else
+        >r dup 0 r>
+        qsort_rec
+    end
+end
+
+# Print all elements of a static array, one per line
+word print_arr
+    dup @ 0
+    while 2dup > do
+        2 pick over arr_get_static puti cr
+        1 +
+    end
+    2drop drop
+end
+
+word main
+    [ 5 3 8 1 7 2 6 4 ] arr_qsort print_arr
+    [ 1 2 3 4 5 ] arr_qsort print_arr
+    [ 9 7 5 3 1 ] arr_qsort print_arr
+    [ 42 ] arr_qsort print_arr
+    [ 3 1 4 1 5 9 2 6 5 3 ] arr_qsort print_arr
+    [ 20 10 ] arr_qsort print_arr
+end