feat: Multi-Directory Workspace Support (part1: add --include-directories option) (#4605)

Co-authored-by: Allen Hutchison <adh@google.com>

packages/cli/src/ui/hooks/atCommandProcessor.test.ts

@@ -57,6 +57,10 @@ describe('handleAtCommand', () => {
         respectGeminiIgnore: true,
       }),
       getEnableRecursiveFileSearch: vi.fn(() => true),
+      getWorkspaceContext: () => ({
+        isPathWithinWorkspace: () => true,
+        getDirectories: () => [testRootDir],
+      }),
     } as unknown as Config;
 
     const registry = new ToolRegistry(mockConfig);