ocaml: phase 1/5/6 float arithmetic +./-./*./. (+5 tests, 372 total)

Tokenizer: +. -. *. /. (with -. avoiding clash with negative float
literals). Parser table places dotted ops at int-precedence levels.
Eval routes to host SX +/-/*//. HM types them Float->Float->Float;
literal floats now infer as Float (was Int).

OCaml-style 1.5 +. 2.5 : Float works end-to-end through tokenize +
parse + eval + infer.

lib/ocaml/test.sh

@@ -910,6 +910,18 @@ cat > "$TMPFILE" << 'EPOCHS'
 (epoch 2203)
 (eval "(ocaml-run \"List.map2 (fun a b -> a + b) [1;2;3] [10;20;30]\")")
 
+;; ── Float arithmetic ───────────────────────────────────────────
+(epoch 2300)
+(eval "(ocaml-run \"1.5 +. 2.5\")")
+(epoch 2301)
+(eval "(ocaml-run \"3.0 *. 2.0\")")
+(epoch 2302)
+(eval "(ocaml-run \"10.0 /. 4.0\")")
+(epoch 2303)
+(eval "(ocaml-type-of \"1.5 +. 2.5\")")
+(epoch 2304)
+(eval "(ocaml-type-of \"fun x y -> x +. y\")")
+
 EPOCHS
 
 OUTPUT=$(timeout 180 "$SX_SERVER" < "$TMPFILE" 2>/dev/null)
@@ -1439,6 +1451,13 @@ check 2201 "List.split"                   '("tuple" (1 2) ("a" "b"))'
 check 2202 "List.fold_left2"              '66'
 check 2203 "List.map2"                    '(11 22 33)'
 
+# ── Float arithmetic ────────────────────────────────────────────
+check 2300 "1.5 +. 2.5"                   '4'
+check 2301 "3.0 *. 2.0"                   '6'
+check 2302 "10.0 /. 4.0"                  '2.5'
+check 2303 "type 1.5 +. 2.5"              '"Float"'
+check 2304 "type fun x y -> x +. y"       '"Float -> Float -> Float"'
+
 TOTAL=$((PASS + FAIL))
 if [ $FAIL -eq 0 ]; then
   echo "ok $PASS/$TOTAL OCaml-on-SX tests passed"