fix(javascript): resolve relative ESM backslash paths (#4323)

Normalize raw URL separators after admitting an original relative ESM
request, before artifact path validation and root confinement. Preserve
the authored declaration and the existing encoded-separator checks.

Retain Node-backed static and dynamic loader controls and compare the
application graph with the historical importer already present on main.
Narrow PR #4323 to this remaining case after the upstream #4269 fix.

Signed-off-by: Jiakai Xu <jiakaiPeanut@gmail.com>

src/application/javascript/JavaScriptArtifactPathResolution.test.ts

@@ -154,6 +154,41 @@ describe("Windows CommonJS request classification", () => {
   });
 });
 
+describe("relative ESM URL separators", () => {
+  it.each([
+    ["./dir\\dep.mjs", "resolved", "app/dir/dep.mjs"],
+    ["../shared\\dep.mjs", "resolved", "shared/dep.mjs"],
+    ["./unused\\..\\dir\\dep.mjs", "resolved", "app/dir/dep.mjs"],
+    ["./..\\..\\outside.mjs", "rejected", null],
+    ["./dir%5cdep.mjs", "rejected", null],
+    ["./dir%2fdep.mjs", "rejected", null],
+    ["./dir\\dep%00.mjs", "rejected", null],
+    [".\\dir\\dep.mjs", "rejected", null],
+  ] as const)(
+    "resolves %s with module URL rules",
+    (declaredPath, status, target) => {
+      expect(
+        resolve({
+          declaredPath,
+          sourcePath: "app/main.mjs",
+          context: "module-specifier",
+          moduleKind: "import",
+          files: fileMap([
+            file("app/main.mjs", "root"),
+            file("app/dir/dep.mjs", "root"),
+            file("shared/dep.mjs", "root"),
+            file("outside.mjs", "root"),
+          ]),
+        }),
+      ).toMatchObject({
+        declared_path: declaredPath,
+        resolution_status: status,
+        resolved_path: target,
+      });
+    },
+  );
+});
+
 describe("literal POSIX inventory base segments", () => {
   it("validates the final URL after a parent reference removes the encoded base segment", () => {
     expect(

src/application/javascript/JavaScriptArtifactPathResolution.ts

@@ -636,7 +636,11 @@ const contextualCandidate = (
   }
   const hasUrlPathSemantics =
     context === "module-specifier" && input.moduleKind === "import";
-  if (hasUrlPathSemantics) declared = htmlUrlText(declared);
+  if (hasUrlPathSemantics) {
+    declared = htmlUrlText(declared);
+    if (isRelativeJavaScriptModuleSpecifier(input.declaredPath))
+      declared = declared.replaceAll("\\", "/");
+  }
   const rejected = rejectDeclaration(
     declared,
     declaresLiteralPercent(input) || hasUrlPathSemantics,