feat: stdlib daily APIs, macro tt/type paste, riscv64 cross smoke

Sessions 83–87: grow Array/Map/String/Test ergonomics; delimiter-balanced
and juxta :tt macros plus $t:type fragments; expression-level $(…),* in
templates; selfhost slice lits; riscv64/aarch64 cross smoke helper and
freestanding docs. Null-safe CBE type names and String_StartsWith.

examples/macro_type.bux

@@ -0,0 +1,55 @@
+// Session 87 — `$t:type` fragment for sizeof / cast type positions
+import Std::Io::{PrintLine, PrintInt};
+import Std::Array::{Array, Array_New, Array_Push, Array_Get, Array_Len, Array_Reverse, Array_Free};
+import Std::Test::{
+    Test_AssertEqInt, Test_AssertEqString, Test_AssertNeqString, Test_Pass
+};
+import Std::String::{String_ToUpper};
+
+macro! size_of {
+    ( $t:type ) => { sizeof($t) as int }
+}
+
+macro! cast_zero {
+    ( $t:type ) => { 0 as $t }
+}
+
+func Main() -> int {
+    let a: int = size_of!(int);
+    let b: int = size_of!(*int);
+    PrintInt(a);
+    PrintLine("");
+    PrintInt(b);
+    PrintLine("");
+    // 4 or 8 depending on ABI
+    if a != 4 && a != 8 {
+        PrintLine("FAIL size_of int");
+        return 1;
+    }
+    if b != 4 && b != 8 {
+        PrintLine("FAIL size_of *int");
+        return 1;
+    }
+
+    let z: int = cast_zero!(int);
+    Test_AssertEqInt(z, 0);
+
+    // Array_Reverse + Test_AssertNeqString
+    var arr: Array<int> = Array_New<int>(4);
+    Array_Push<int>(&arr, 1);
+    Array_Push<int>(&arr, 2);
+    Array_Push<int>(&arr, 3);
+    Array_Reverse<int>(&arr);
+    Test_AssertEqInt(Array_Get<int>(&arr, 0), 3);
+    Test_AssertEqInt(Array_Get<int>(&arr, 1), 2);
+    Test_AssertEqInt(Array_Get<int>(&arr, 2), 1);
+    Test_AssertEqInt(Array_Len<int>(&arr) as int, 3);
+    Array_Free<int>(&arr);
+
+    Test_AssertEqString(String_ToUpper("ok"), "OK");
+    Test_AssertNeqString("a", "b");
+
+    PrintLine("PASS macro_type");
+    Test_Pass("macro_type");
+    return 0;
+}