noun: fix Lagoon argmin/argmax jets to return the forward (ravel) index

The argmin/argmax jets computed the result index as `len_x - i - 1`
(reversed), so the jetted index disagreed with the Hoon (which returns the
forward ravel index of the first extremum) and with the unjetted interpreter
whenever the extremum was not at index 0 -- a silent jet/Hoon mismatch.

Use the forward index `i`.  Upstreams the numerics fix (urbit/numerics#29,
already in the numerics master copy but never carried into the runtime).

Verified on a hoon-135 fakezod: for a 3-vector with its min/max at logical
index 2, the jet now returns 2 (was 0), matching the unjetted Hoon.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: sigilante

pkg/noun/jets/i/lagoon.c

@@ -589,7 +589,7 @@
         for (c3_d i = 0; i < len_x; i++) {
            if(f16_lt(((float16_t*)x_bytes)[i], min_val16)) {
              min_val16 = ((float16_t*)x_bytes)[i];
-             min_idx = (len_x - i - 1);
+             min_idx = i;
            }
         }
         break;}
@@ -599,7 +599,7 @@
         for (c3_d i = 0; i < len_x; i++) {
            if(f32_lt(((float32_t*)x_bytes)[i], min_val32)) {
              min_val32 = ((float32_t*)x_bytes)[i];
-             min_idx = (len_x - i - 1);
+             min_idx = i;
            }
         }
         break;}
@@ -609,7 +609,7 @@
         for (c3_d i = 0; i < len_x; i++) {
            if(f64_lt(((float64_t*)x_bytes)[i], min_val64)) {
              min_val64 = ((float64_t*)x_bytes)[i];
-             min_idx = (len_x - i - 1);
+             min_idx = i;
            }
         }
         break;}
@@ -619,7 +619,7 @@
         for (c3_d i = 0; i < len_x; i++) {
            if(f128M_lt(&(((float128_t*)x_bytes)[i]), &min_val128)) {
              min_val128 = *f128M_min(&min_val128, &((float128_t*)x_bytes)[i]);
-             min_idx = (len_x - i - 1);
+             min_idx = i;
            }
         }
         break;}
@@ -662,7 +662,7 @@
         for (c3_d i = 0; i < len_x; i++) {
            if(f16_gt(((float16_t*)x_bytes)[i], max_val16)) {
              max_val16 = ((float16_t*)x_bytes)[i];
-             max_idx = (len_x - i - 1);
+             max_idx = i;
            }
         }
         break;}
@@ -672,7 +672,7 @@
         for (c3_d i = 0; i < len_x; i++) {
            if(f32_gt(((float32_t*)x_bytes)[i], max_val32)) {
              max_val32 = ((float32_t*)x_bytes)[i];
-             max_idx = (len_x - i - 1);
+             max_idx = i;
            }
         }
         break;}
@@ -682,7 +682,7 @@
         for (c3_d i = 0; i < len_x; i++) {
            if(f64_gt(((float64_t*)x_bytes)[i], max_val64)) {
              max_val64 = ((float64_t*)x_bytes)[i];
-             max_idx = (len_x - i - 1);
+             max_idx = i;
            }
         }
         break;}
@@ -692,7 +692,7 @@
         for (c3_d i = 0; i < len_x; i++) {
            if(f128M_gt(&(((float128_t*)x_bytes)[i]), &max_val128)) {
              max_val128 = *f128M_max(&max_val128, &((float128_t*)x_bytes)[i]);
-             max_idx = (len_x - i - 1);
+             max_idx = i;
            }
         }
         break;}