Refactor plugin architecture, isolate Windows-spefic code

tests/process/WindowsProcess.test.ts

@@ -0,0 +1,26 @@
+import { describe, test, expect } from "bun:test";
+import { WindowsProcess } from "../../src/server/process/WindowsProcess";
+
+describe.skipIf(process.platform !== "win32")("WindowsProcess", () => {
+  const processImpl = new WindowsProcess();
+
+  describe("verifyCommand", () => {
+    test("returns null for existing executable in PATH", async () => {
+      // 'cmd' should exist on all Windows systems
+      const result = await processImpl.verifyCommand("cmd");
+      expect(result).toBeNull();
+    });
+
+    test("returns error message for non-existent executable", async () => {
+      const nonExistentPath = "C:\\nonexistent\\path\\to\\executable.exe";
+      const result = await processImpl.verifyCommand(nonExistentPath);
+      expect(result).toContain("Executable not found");
+      expect(result).toContain(nonExistentPath);
+    });
+
+    test("returns error for non-existent command in PATH", async () => {
+      const result = await processImpl.verifyCommand("definitely-not-a-real-command-12345");
+      expect(result).toContain("Executable not found");
+    });
+  });
+});