ocaml: phase 6 Option/Result/Bytes extensions (+9 tests, 439 total)

Option: join, to_result, some, none.
Result: value, iter, fold.
Bytes: length, get, of_string, to_string, concat, sub — thin alias of
String (SX has no separate immutable byte type).

Ordering fix: Bytes module placed after String so its closures capture
String in scope. Earlier draft put Bytes before String which made
String.* lookups fail with 'not a record/module' (treated as nullary
ctor).

lib/ocaml/test.sh

@@ -1064,6 +1064,26 @@ cat > "$TMPFILE" << 'EPOCHS'
 (epoch 3604)
 (eval "(ocaml-run-program \"let q = Queue.create () ;; Queue.push 1 q ;; Queue.push 2 q ;; Queue.length q\")")
 
+;; ── Option/Result/Bytes extensions ────────────────────────────
+(epoch 3700)
+(eval "(ocaml-run \"Option.join (Some (Some 5))\")")
+(epoch 3701)
+(eval "(ocaml-run \"Option.join None\")")
+(epoch 3702)
+(eval "(ocaml-run \"Option.to_result \\\"missing\\\" None\")")
+(epoch 3703)
+(eval "(ocaml-run \"Option.to_result \\\"missing\\\" (Some 7)\")")
+(epoch 3704)
+(eval "(ocaml-run \"Result.value (Ok 5) 0\")")
+(epoch 3705)
+(eval "(ocaml-run \"Result.value (Error \\\"e\\\") 99\")")
+(epoch 3706)
+(eval "(ocaml-run \"Result.fold (fun x -> x * 10) (fun e -> 0) (Ok 5)\")")
+(epoch 3707)
+(eval "(ocaml-run \"Bytes.length \\\"hello\\\"\")")
+(epoch 3708)
+(eval "(ocaml-run \"Bytes.concat \\\"-\\\" [\\\"a\\\";\\\"b\\\";\\\"c\\\"]\")")
+
 EPOCHS
 
 OUTPUT=$(timeout 180 "$SX_SERVER" < "$TMPFILE" 2>/dev/null)
@@ -1684,6 +1704,17 @@ check 3602 "Stack.top"                    '1'
 check 3603 "Queue.pop FIFO"               '1'
 check 3604 "Queue.length"                 '2'
 
+# ── Option/Result/Bytes extensions ─────────────────────────────
+check 3700 "Option.join nested"           '("Some" 5)'
+check 3701 "Option.join None"             '("None")'
+check 3702 "Option.to_result None"        '("Error" "missing")'
+check 3703 "Option.to_result Some"        '("Ok" 7)'
+check 3704 "Result.value Ok"              '5'
+check 3705 "Result.value Error fallback"  '99'
+check 3706 "Result.fold Ok"               '50'
+check 3707 "Bytes.length"                 '5'
+check 3708 "Bytes.concat"                 '"a-b-c"'
+
 TOTAL=$((PASS + FAIL))
 if [ $FAIL -eq 0 ]; then
   echo "ok $PASS/$TOTAL OCaml-on-SX tests passed"