docs: add inlineDemo tracing example (leaf helper, two sites) (#232)

A small leaf helper square(x) called from two sites with
storage-read args. At O2/O3 both sites inline into the caller ->
two virtual activations in the tracer (the inline showcase, as
sum/factorial were for tailcall). Args are non-constant (storage
reads) so L1 fold can't collapse the inlined bodies.

Verified against bugc: correct result (3^2 + 4^2 = 25) at O0-O3;
zero inline marks at O0/O1, both sites inlined at O2 (108 -> 50
runtime instrs) and O3.

Prose + TraceExample wiring to follow (writer/docs).

Author: gnidan

packages/web/docs/core-schemas/programs/tracing-examples.ts

@@ -138,3 +138,27 @@ create {
 code {
   result = fact(5, 1);
 }`;
+
+export const inlineDemo = `name InlineDemo;
+
+define {
+  function square(x: uint256) -> uint256 {
+    return x * x;
+  };
+}
+
+storage {
+  [0] a: uint256;
+  [1] b: uint256;
+  [2] sumOfSquares: uint256;
+}
+
+create {
+  a = 3;
+  b = 4;
+  sumOfSquares = 0;
+}
+
+code {
+  sumOfSquares = square(a) + square(b);
+}`;