fix(resolution): resolve ES imports targeting .xsjs/.xsjslib files (#556) (#594)

The extraction half of #556 — indexing `.xsjs` / `.xsjslib` as JavaScript — already
landed on main via #654. This PR is now scoped to the remaining resolution gap:
the JS import-resolution list did not include the SAP HANA extensions, so an
extensionless `import { x } from './helpers'` in a `.xsjs` file resolved to
nothing and the cross-file call edge was dropped.

Add `.xsjs` / `.xsjslib` to the `javascript` entry in EXTENSION_RESOLUTION so
those imports resolve to their target file and `codegraph_callers` /
`codegraph_impact` see the edge. One resolution test covers the .xsjs -> .xsjslib
import; the now-redundant extraction/detection tests were dropped (covered by #654).

src/resolution/import-resolver.ts

@@ -26,7 +26,7 @@ const EXTENSION_RESOLUTION: Record<string, string[]> = {
   // module-entry convention, hit when a bare workspace import ("data") is
   // rewritten to the member's directory; lowercase variants for safety.
   arkts: ['.ets', '.ts', '.d.ts', '.js', '/Index.ets', '/index.ets', '/index.ts', '/index.js'],
-  javascript: ['.js', '.jsx', '.mjs', '.cjs', '/index.js', '/index.jsx'],
+  javascript: ['.js', '.jsx', '.mjs', '.cjs', '.xsjs', '.xsjslib', '/index.js', '/index.jsx'],
   tsx: ['.tsx', '.ts', '.d.ts', '.js', '.jsx', '/index.tsx', '/index.ts', '/index.js'],
   jsx: ['.jsx', '.js', '/index.jsx', '/index.js'],
   // SFC consumers import plain TS/JS, sibling components, and barrels