ocaml: phase 5.1 daily_temperatures.ml baseline (sum of waits = 10)

Monotonic decreasing stack — for each day i, pop entries from
the stack whose temperature is strictly less than today's; their
answer is (i - popped_index).

  temps  = [73; 74; 75; 71; 69; 72; 76; 73]
  answer = [ 1;  1;  4;  2;  1;  1;  0;  0]
  sum    = 10

Complementary to next_greater.ml (iter 256) — same monotonic-stack
skeleton but stores the distance to the next greater element
rather than its value.

Tests `match !stack with | top :: rest when …` pattern with
guard inside a while-cont-flag loop.

198 baseline programs total.

plans/ocaml-on-sx.md

@@ -407,6 +407,16 @@ _Newest first._
   binary search tree (`type 'a tree = Leaf | Node of 'a * 'a tree *
   'a tree`) with insert + in-order traversal. Tests parametric ADT,
   recursive match, List.append, List.fold_left.
+- 2026-05-11 Phase 5.1 — daily_temperatures.ml baseline (monotonic
+  decreasing stack of waiting days until warmer; sum over
+  [73;74;75;71;69;72;76;73] = 10). For each day i, pop all stack
+  entries whose temperature is strictly less than today's,
+  recording `i - top` for each. Result vector [1,1,4,2,1,1,0,0]
+  sums to 10. Complementary to next_greater.ml — same monotonic-
+  stack skeleton but stores the distance to the next greater
+  element instead of its value. Tests pattern `match !stack with
+  | top :: rest when condition -> … | _ -> exit` inside while.
+  198 baseline programs total.
 - 2026-05-11 Phase 5.1 — count_bits.ml baseline (sum of popcount for
   0..100 = 319). DP recurrence: popcount(i) = popcount(i/2) +
   (i mod 2) — drop the low bit and recurse, adding back the bit