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/javascriptSemanticAnalysis.rejection.test.ts

@@ -144,7 +144,11 @@ describe("JavaScript semantic analysis: rejection 1", () => {
     expect(recovered.returnSites[0]?.value).toMatchObject({
       status: "object",
       properties: expect.arrayContaining([
-        { name: "type", value: { status: "literal", value: "item" } },
+        {
+          name: "type",
+          presence: "present",
+          value: { status: "literal", value: "item" },
+        },
         expect.objectContaining({
           name: "text",
           value: expect.objectContaining({ status: "unknown" }),