fix: handle OS-level absolute paths in module resolver

The module resolver was incorrectly treating OS-level absolute paths (like /Users/...)
as project-relative paths (like /module), causing path duplication when resolving
entry points. This fix distinguishes between the two by checking if the absolute
path has multiple path segments.

The issue occurred because:
1. The resolver checked for absolute paths with fs.existsSync()
2. If the file didn't exist or the check failed, it fell through to the project-relative handler
3. The project-relative handler (resolveAbsolute) would strip the leading '/' and
   concatenate with baseUrl, causing duplication

The fix checks if an absolute path has multiple segments (e.g., /Users/foo/bar vs /module)
to determine if it's an OS-level absolute path or a project-relative path.

Fixes the issue where 'somon run hello_world.som' would fail with a duplicated path error.

Author: Bakhtier Gaibulloev

src/module-system/module-resolver.ts

@@ -55,12 +55,19 @@ export class ModuleResolver {
     }
 
     // Handle already absolute file paths
-    if (path.isAbsolute(specifier) && fs.existsSync(specifier)) {
-      return {
-        resolvedPath: specifier,
-        isExternalLibrary: false,
-        extension: path.extname(specifier),
-      };
+    // Check if it's an OS-level absolute path (not project-relative like "/module")
+    // We distinguish by checking if it's absolute AND has path separators beyond the first character
+    if (path.isAbsolute(specifier)) {
+      const normalizedPath = path.normalize(specifier);
+      // If the path has multiple segments (e.g., /Users/... or C:\Users\...), treat as OS absolute
+      const pathSegments = normalizedPath.split(path.sep).filter(s => s.length > 0);
+      if (pathSegments.length > 1) {
+        return {
+          resolvedPath: normalizedPath,
+          isExternalLibrary: false,
+          extension: path.extname(normalizedPath),
+        };
+      }
     }
 
     // Handle relative imports (./module, ../module)