ocaml: phase 6 Random module (deterministic LCG) (+4 tests, 549 total)

Linear-congruential PRNG with mutable seed (_state ref). API:

  init s        seed the PRNG
  self_init ()  default seed (1)
  int bound     0 <= n < bound
  bool ()       fair coin
  float bound   uniform in [0, bound)
  bits ()       30 bits

Stepping rule:
  state := (state * 1103515245 + 12345) mod 2147483647
  result := |state| mod bound

Same seed reproduces the same sequence. Real OCaml's Random uses
Lagged Fibonacci; ours is simpler but adequate for shuffles and
Monte Carlo demos in baseline programs.

  Random.init 42; Random.int 100  = 48
  Random.init 1;  Random.int 10   = 0

lib/ocaml/test.sh

@@ -1360,6 +1360,16 @@ cat > "$TMPFILE" << 'EPOCHS'
 (epoch 5103)
 (eval "(ocaml-run \"let t = Hashtbl.create 4 in Hashtbl.add t \\\"a\\\" 1; Hashtbl.clear t; Hashtbl.length t\")")
 
+;; ── Random module (deterministic LCG) ─────────────────────────
+(epoch 5110)
+(eval "(ocaml-run \"Random.init 42; Random.int 100\")")
+(epoch 5111)
+(eval "(ocaml-run \"Random.init 42; let a = Random.int 100 in let b = Random.int 100 in let c = Random.int 100 in a + b + c\")")
+(epoch 5112)
+(eval "(ocaml-run \"Random.init 1; Random.int 10\")")
+(epoch 5113)
+(eval "(ocaml-run \"Random.init 7; Random.bool ()\")")
+
 EPOCHS
 
 OUTPUT=$(timeout 360 "$SX_SERVER" < "$TMPFILE" 2>/dev/null)
@@ -2161,6 +2171,12 @@ check 5101 "Hashtbl.values sum"           '12'
 check 5102 "Hashtbl.remove + length"      '1'
 check 5103 "Hashtbl.clear + length"       '0'
 
+# ── Random (deterministic LCG) ──────────────────────────────────
+check 5110 "Random.int 100 seed=42"       '48'
+check 5111 "Random.int x3 seed=42 sum"    '152'
+check 5112 "Random.int 10 seed=1"         '0'
+check 5113 "Random.bool seed=7"           'true'
+
 TOTAL=$((PASS + FAIL))
 if [ $FAIL -eq 0 ]; then
   echo "ok $PASS/$TOTAL OCaml-on-SX tests passed"