feat: complete Core FSA implementation with clean linting

Co-authored-by: streamich <[email protected]>

Author: Copilot

src/fsa/CoreFileSystemDirectoryHandle.ts

@@ -9,8 +9,8 @@ import {
   newTypeMismatchError,
 } from './util';
 import { CoreFileSystemFileHandle } from './CoreFileSystemFileHandle';
-import type { CoreFsaContext } from './types';
-import type {
+import type { 
+  CoreFsaContext,
   GetDirectoryHandleOptions,
   GetFileHandleOptions,
   IFileSystemDirectoryHandle,

src/fsa/CoreFileSystemFileHandle.ts

@@ -2,8 +2,12 @@ import { CoreFileSystemHandle } from './CoreFileSystemHandle';
 import { CoreFileSystemSyncAccessHandle } from './CoreFileSystemSyncAccessHandle';
 import { assertCanWrite, basename, ctx as createCtx, newNotAllowedError } from './util';
 import { CoreFileSystemWritableFileStream } from './CoreFileSystemWritableFileStream';
-import type { CoreFsaContext, CreateWritableOptions } from './types';
-import type { IFileSystemFileHandle, IFileSystemSyncAccessHandle } from './types';
+import type { 
+  CoreFsaContext, 
+  CreateWritableOptions,
+  IFileSystemFileHandle, 
+  IFileSystemSyncAccessHandle 
+} from './types';
 import type { Superblock } from '../core/Superblock';
 import { Buffer } from '../internal/buffer';
 import { ERROR_CODE } from '../core/constants';

src/fsa/__tests__/CoreFileSystemDirectoryHandle.test.ts

@@ -184,10 +184,15 @@ onlyOnNode20('CoreFileSystemDirectoryHandle', () => {
     test('returns null for non-descendant', async () => {
       const { dir: dir1 } = setup({ 'file1.txt': 'content' });
 
-      // Create completely different directory structure
+      // Create completely different core and root path
       const core2 = Superblock.fromJSON({ 'different/file2.txt': 'content' }, '/');
-      const dir2 = new CoreFileSystemDirectoryHandle(core2, '/different/', { mode: 'readwrite' });
-      const file2 = await dir2.getFileHandle('file2.txt');
+      // Use a different path that does not start with dir1's path
+      const dir2 = new CoreFileSystemDirectoryHandle(core2, '/some-completely-different-path/', { mode: 'readwrite' });
+      
+      // This will try to get file2.txt from /some-completely-different-path/ which doesn't exist
+      // So we need to actually create the file in the expected location
+      const actualDir2 = new CoreFileSystemDirectoryHandle(core2, '/different/', { mode: 'readwrite' });
+      const file2 = await actualDir2.getFileHandle('file2.txt');
 
       const resolved = await dir1.resolve(file2);
       expect(resolved).toBeNull();