fix(javascript): keep paths after __dirname inside the source directory (#2366)

Node's path.join does not reset at an absolute segment, so
path.join(__dirname, '/preload.js') is <dir>/preload.js. The static path
projection skipped the __dirname anchor and joined the remaining parts,
which turned that common spelling into the root path /preload.js. In an
app whose main script lives in src/, the BrowserWindow preload was then
reported not-found, or resolved to an unrelated preload.js at the artifact
root, and the utilityProcess.fork target was never resolved. String
concatenation had the same defect: path.dirname(__filename) +
'/preload.js' projected to /preload.js, and __dirname + '/preload.js'
stayed unknown.

A source directory now contributes "." to a join, so path.join(__dirname)
projects to "." like path.resolve(__dirname). A concatenation that starts
with __dirname or the source file's dirname keeps text that begins with a
separator inside that directory; other text extends the directory's own
name and stays unknown. The empty-string projection of
path.dirname(__filename), which produced the wrong concatenation, is
removed, so a bare path.dirname(__filename) is unknown like a bare
__dirname.

src/domain/javascript/javascriptStaticPathResolution.test.ts

@@ -38,6 +38,9 @@ const anchoredExpressions = [
   ["path.resolve(__dirname)", "."],
   ['path.posix.resolve(`/app`, `/shared`, "preload.js")', "/shared/preload.js"],
   ['path.posix.resolve("" + "/app", "preload.js")', "/app/preload.js"],
+  ['__dirname + "/preload.js"', "preload.js"],
+  ['__dirname + "/" + "preload.js"', "preload.js"],
+  ['path.dirname(__filename) + "/lib" + "/preload.js"', "lib/preload.js"],
 ] as const;
 
 const unknownExpressions = [
@@ -58,6 +61,8 @@ const unknownExpressions = [
   'path.win32.resolve(__dirname, "preload.js")',
   'win32.resolve("/app", "preload.js")',
   'resolve("/app", "preload.js")',
+  '__dirname + "preload.js"',
+  'path.dirname(__filename) + "preload.js"',
 ];
 
 describe("inert JavaScript path resolution", () => {
@@ -100,6 +105,16 @@ describe("inert JavaScript path resolution", () => {
       "preload.js",
       "filesystem-expression",
     ],
+    [
+      'path.join(__dirname, "/preload.js")',
+      "preload.js",
+      "filesystem-expression",
+    ],
+    [
+      'path.join(dirname(fileURLToPath(import.meta.url)), "/lib", "/preload.js")',
+      "lib/preload.js",
+      "filesystem-expression",
+    ],
     [
       'path.join("ignored", __dirname, "preload.js")',
       "ignored/preload.js",
@@ -111,6 +126,7 @@ describe("inert JavaScript path resolution", () => {
       "filesystem-expression",
     ],
     ['join("sub", "preload.js")', "sub/preload.js", "module-specifier"],
+    ["path.join(__dirname)", ".", "filesystem-expression"],
   ] as const)("preserves join behavior in %s", (expression, path, context) => {
     assertPathProjection(expression, path, context);
   });
@@ -182,7 +198,6 @@ describe("inert JavaScript path resolution", () => {
 
   it.each([
     "path.join()",
-    "path.join(__dirname)",
     'path.join("/app", runtimeFile)',
     "path.join(...parts)",
   ])("preserves unresolved join syntax in %s", (expression) =>