fix(js,ts): an import spelled with a trailing slash or a ./ segment links its file (#2792)

Issue 2577: `import('@/widgets/Chart/')`, `from 'src/widgets/./Chart'`, a
doubled slash, a `..` after an alias, and a workspace package's
`from '@acme/ui/'` lost the edges the plain spelling gets. The file import
was dropped, the names were matched by name alone, and the lazily loaded
component rendered the importing file's own `lazy(...)` constant.

Root cause: the fallback-alias, workspace, direct-path and own-config
branches of the import resolver join the specifier as written and probe
the result through tryWithExtensions. `fileExists` falls back to the disk,
which accepts any spelling of a file, so the resolver returned
`src/widgets/Chart//index.tsx` or `src/widgets/./Chart/index.tsx`, and every
lookup keyed by the indexed path missed it. The relative and tsconfig-path
branches go through path.resolve and were already fine.

Fix (import-resolver.ts): tryWithExtensions spells each candidate as the
index keys files (indexedSpelling): for the ES module family, a path with a
doubled slash or a `.`/`..` segment is posix-normalized before it is probed
and returned. That is how Node, tsc and the bundlers read a specifier. A
trailing slash still names only a folder, because `Chart/` plus `.tsx` is
no file. Other languages are untouched: a C include's `a/../b.h` follows the
folder on disk, as PR 2610 noted.

Validation:
- __tests__/import-path-spelling.test.ts: 4 of 5 fail on main (the plain
  spelling passes). They cover the issue's spellings, a doubled slash, `..`,
  a trailing slash beside a same-named file, and a workspace member. All
  pass on the kernel and with CODEGRAPH_KERNEL=0. Dropping the
  normalization, or its doubled-slash check, fails 4.
- Sync equals a fresh index (CLI) when the folder arrives after its
  importer, when the importer is re-spelled, when the folder is deleted
  and when the target is edited.
- A/B on 11 TS/JS repos plus 2 controls, both arms with the kernel:
  pulse-sms-web (53 imports like '@/utils/') gains 65 edges and corrects
  7, including 2 imports that had name-matched to same-named API classes;
  react-one gains 11 file imports and corrects 2 bindings. All 85 are right.
  The other nine (jvue-admin, vue-invoice-app, vue3-antdv-admin, v-ui,
  vue-blog-admin, dreammart, vite, outline, social-app) and the flask and
  gin controls are byte-identical.
- Cost: fresh index, median of 3 interleaved: vite 7.59 s main vs 7.49 s,
  outline 16.63 s vs 16.94 s.

Fixes #2577

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/resolution/import-resolver.ts

@@ -1330,14 +1330,38 @@ function resolveAliasedImport(
   return tryWithExt(importPath);
 }
 
-/** The file `basePath` names: with the language's extensions or index files, as is, or as an emitted `.js`. */
+/**
+ * The file `basePath` names: with the language's extensions or index files, as
+ * is, or as an emitted `.js` — each spelled as the index keys it
+ * (indexedSpelling).
+ */
 function tryWithExtensions(basePath: string, language: Language, context: ResolutionContext): string | null {
   for (const ext of EXTENSION_RESOLUTION[language] || []) {
-    const candidate = basePath + ext;
+    const candidate = indexedSpelling(basePath + ext, language);
     if (context.fileExists(candidate)) return candidate;
   }
-  if (context.fileExists(basePath)) return basePath;
-  return findSourceForEmittedSpecifier(basePath, language, context);
+  const asIs = indexedSpelling(basePath, language);
+  if (context.fileExists(asIs)) return asIs;
+  return findSourceForEmittedSpecifier(asIs, language, context);
+}
+
+/**
+ * A path as the index keys its files. The alias, workspace and direct-path
+ * branches join an import specifier as written, so `@/widgets/Chart/` made
+ * `src/widgets/Chart//index.tsx` and `src/widgets/./Chart` made
+ * `src/widgets/./Chart/index.tsx`. The disk check accepts either spelling, but
+ * no file node or `files` row is keyed by it, so the import linked nothing
+ * (#2577). An ES module specifier is read lexically — by Node, tsc and the
+ * bundlers alike — so `.` and empty segments drop out and `..` folds, here as
+ * there. A trailing slash still names a folder: `Chart/` gives
+ * `Chart/index.tsx`, never `Chart.tsx`. Other languages keep the path as
+ * found: a C include's `a/../b.h` follows the folder `a` on disk, symlinks
+ * included.
+ */
+function indexedSpelling(filePath: string, language: Language): string {
+  return ESM_IMPORT_LANGUAGES.has(language) && /\/\/|(?:^|\/)\.\.?(?:\/|$)/.test(filePath)
+    ? path.posix.normalize(filePath)
+    : filePath;
 }
 
 /**