fix(javascript)!: preserve property paths and uncertain slot presence

Use one explicit object/array slot model and JSON-pointer property identity across mutation analysis, return projection, and semantic graphs. Require observed presence for discriminants and resolve writes only through retained object or array receivers.

BREAKING CHANGE: projected return fields require explicit presence and semantic object operations carry full property paths.

src/domain/javascript/javascriptExportShapeComparisonSchemas.ts

@@ -75,7 +75,7 @@ export const compareJavaScriptExportShapesInputSchema = z
 
 const projectedReturnFieldShape = {
   path: jsonPointerSchema,
-  presence: z.enum(["present", "absent", "unknown-coverage"]).optional(),
+  presence: z.enum(["present", "absent", "unknown-coverage"]),
 };
 const projectedReturnFieldSchema = z.discriminatedUnion("state", [
   z.strictObject({