feat(javascript): report observed export property presence (#1160)

* feat(javascript): report observed export property presence

Extend compare_javascript_export_shapes so each retained return variant
lists observed property names and each change reports presence independently
of value resolution. Complete parent coverage classifies one-sided names as
added or removed even when static values stay unknown.

Fixes #725

* test(javascript): match unknown export-shape values by availability

Nested availability objects include a reason when values stay unresolved.
Assert availability through objectContaining so presence-only added and
removed rows still verify unknown values.

* fix(javascript): preserve uncertain export property presence and locations

* fix(javascript): normalize presence and preserve local property coverage

* fix(javascript): require present discriminants for return pairing

* fix(javascript): normalize retained shapes before comparison

* refactor(javascript): share return projection with executable examples

* fix(javascript): localize uncertainty for missing mutated slots

* fix(javascript): bind advertised export examples to exact artifacts

* fix(javascript): keep uncertain property flow as candidates

---------

Co-authored-by: morluto <76467478+morluto@users.noreply.github.com>

src/domain/javascript/javascriptExportShapeComparison.ts

@@ -17,6 +17,7 @@ import {
 } from "./javascriptExportShapeSelection.js";
 import {
   buildJavaScriptExportShapeChanges,
+  buildJavaScriptExportShapeInventories,
   hasPartialJavaScriptExportPropertyCoverage,
   pairJavaScriptExportShapeVariants,
   type JavaScriptExportShapePairing,
@@ -56,6 +57,11 @@ export const compareJavaScriptExportShapes = (
   );
   const changes = allChanges;
   const omittedChanges = 0;
+  const propertyInventories = buildJavaScriptExportShapeInventories({
+    pairing,
+    leftShapes: leftRetained.shapes,
+    rightShapes: rightRetained.shapes,
+  });
   const coverage = comparisonCoverage({
     input,
     left,
@@ -70,6 +76,7 @@ export const compareJavaScriptExportShapes = (
   const semantic = {
     left: left.selection,
     right: right.selection,
+    property_inventories: propertyInventories,
     summary: summarize(allChanges),
     changes,
     coverage,