Phase 7j: words buffers + w[i] word indexing (retire peek32/poke32)

32-bit word access is indexing now, not peek32/poke32:

  peek32(ui_rx, i)       -> ui_rx[i]        (reads an int)
  poke32(rt_fb, i, c)    -> rt_fb[i] = c    (writes an int)

A buffer typed `words` (a pointer whose elements are i32) indexes with `w[i]`
as a full int; a plain `ptr`/`str` keeps byte indexing. emit_index_addr picks the
element type from the base's type — byte-identical IR to the old intrinsics, so
the migration reproduces the compiler and every golden render exactly.

The ~60 word buffers (rt_fb, tt_*/gc_* font tables, png_px/spr_px pixels, ui_*
layout arrays) were retyped from `ptr` to `words` scope-aware (per-function, so
the s/out/p byte-vs-word name collisions across functions stay correct), then the
254 peek32/poke32 sites migrated to indexing. A scope-analysis miss left 12
buffers (gc_*, sc_d, ui_rx/ui_ry) un-retyped — caught as a menu golden diff and
fixed. No true mixed byte+word access exists on any one variable, so a per-buffer
element type is sound.

Reseeded (22527 lines); C-free fixpoint holds; goldens byte-identical; 18/18;
vocab (byte/words types in, peek32/poke32 out) + doc-fences clean.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

selfhost/emit_addr.ludic

@@ -21,9 +21,14 @@ fn emit_member_addr(e: Node) -> ptr {
 # address of `base[index]` (slices only in this subset)
 fn emit_index_addr(e: Node) -> ptr {
   let base = emit_expr(e.a)
-  if not is_slice_ty(base.ty) {                   # a raw ptr/str: address of byte i.
+  if not is_slice_ty(base.ty) {                   # a raw pointer: address of element i
     let bi = emit_expr(e.b)                        # (evaluate index first — it may set g_addr_ty)
-    let r = emit_bind(`getelementptr inbounds i8, ptr {base.code}, i32 {bi.code}`)
+    if (base.ty == "words") {                      # a `words` buffer: 32-bit elements
+      let rw = emit_bind(`getelementptr inbounds i32, ptr {base.code}, i32 {bi.code}`)
+      g_addr_ty = "int"
+      return rw
+    }
+    let r = emit_bind(`getelementptr inbounds i8, ptr {base.code}, i32 {bi.code}`)   # a ptr/str: bytes
     g_addr_ty = "byte"                             # set last so the caller sees it
     return r
   }

selfhost/emit_core.ludic

@@ -54,6 +54,7 @@ fn lbl(pfx: ptr) -> ptr { let r = (pfx + itoa(ll_lbl));  ll_lbl = ll_lbl + 1;  r
 fn llty(t: ptr) -> ptr {
   if (t == "int") or (t == "bool") or (t == "fixed") { return "i32" }
   if (t == "byte") { return "i8" }                # a single byte (p[i] on a raw ptr)
+  if (t == "words") { return "ptr" }              # a 32-bit-word buffer (w[i] is i32)
   if (t == "void") { return "void" }
   return "ptr"
 }

selfhost/emit_intrin.ludic

@@ -13,7 +13,6 @@ fn is_intrinsic(name: ptr) -> bool {
   if (name == "os_argc") or (name == "os_arg") or (name == "os_exit") or (name == "file_stderr") { return true }
   if (name == "file_stdout") { return true }
   if (name == "os_system") or (name == "os_getenv") { return true }
-  if (name == "peek32") or (name == "poke32") { return true }
   return false
 }
 # emit "  <r> = <rest>\n" and return r
@@ -87,19 +86,7 @@ fn emit_intrinsic(name: ptr, e: Node) -> Val {
     return val(emit_bind(`call ptr @getenv(ptr {n})`), "str")
   }
   # bitwise ops are the operators & | ^ << >> ~ now (see emit_bin / p_mul).
-  if (name == "peek32") {
-    let p = arg_code(e, 0);  let i = arg_code(e, 1)
-    let g = nreg()
-    emit("  ");  emit(g);  emit(" = getelementptr inbounds i32, ptr ");  emit(p);  emit(", i32 ");  emit(i);  emit("\n")
-    return val(emit_bind(`load i32, ptr {g}`), "int")
-  }
-  if (name == "poke32") {
-    let p = arg_code(e, 0);  let i = arg_code(e, 1);  let v = arg_code(e, 2)
-    let g = nreg()
-    emit("  ");  emit(g);  emit(" = getelementptr inbounds i32, ptr ");  emit(p);  emit(", i32 ");  emit(i);  emit("\n")
-    emit("  store i32 ");  emit(v);  emit(", ptr ");  emit(g);  emit("\n")
-    return val("0", "void")
-  }
+  # peek32 / poke32 are `words` indexing now: w[i] and w[i] = v (see emit_index_addr).
   g_intrin_ok = false
   return val("0", "void")
 }

selfhost/tests/match_bits.ludic

@@ -10,7 +10,7 @@ program T {
     print((1 << 4))             # 16
     print(((4 | 1) & 6))    # 4
     let p = mem_alloc(16)
-    poke32(p, 1, 9999)
-    print(peek32(p, 1))          # 9999
+    p[1] = 9999
+    print(p[1])          # 9999
   }
 }