spec: bitwise operations (bitwise-and/or/xor/not, arithmetic-shift, bit-count, integer-length)

OCaml: land/lor/lxor/lnot/lsl/asr in sx_primitives.ml
JS: & | ^ ~ << >> with Kernighan popcount and Math.clz32 for integer-length
spec/primitives.sx: stdlib.bitwise module with 7 entries
26 tests, 158 assertions, all pass OCaml+JS

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

hosts/javascript/platform.py

@@ -1309,6 +1309,27 @@ PRIMITIVES_JS_MODULES: dict[str, str] = {
     return NIL;
   };
 ''',
+
+    "stdlib.bitwise": '''
+  // stdlib.bitwise
+  PRIMITIVES["bitwise-and"] = function(a, b) { return (a & b) | 0; };
+  PRIMITIVES["bitwise-or"]  = function(a, b) { return (a | b) | 0; };
+  PRIMITIVES["bitwise-xor"] = function(a, b) { return (a ^ b) | 0; };
+  PRIMITIVES["bitwise-not"] = function(a)    { return ~a; };
+  PRIMITIVES["arithmetic-shift"] = function(a, count) {
+    return count >= 0 ? (a << count) | 0 : a >> (-count);
+  };
+  PRIMITIVES["bit-count"] = function(a) {
+    var n = Math.abs(a) >>> 0;
+    n = n - ((n >> 1) & 0x55555555);
+    n = (n & 0x33333333) + ((n >> 2) & 0x33333333);
+    return (((n + (n >> 4)) & 0x0f0f0f0f) * 0x01010101) >>> 24;
+  };
+  PRIMITIVES["integer-length"] = function(a) {
+    if (a === 0) return 0;
+    return 32 - Math.clz32(Math.abs(a));
+  };
+''',
 }
 # Modules to include by default (all)
 _ALL_JS_MODULES = list(PRIMITIVES_JS_MODULES.keys())