fix(desktop): change detection on Windows, especially Cygwin (#13659)

Co-authored-by: LukeParkerDev <10430890+Hona@users.noreply.github.com>

packages/opencode/test/util/filesystem.test.ts

@@ -286,6 +286,40 @@ describe("filesystem", () => {
     })
   })
 
+  describe("windowsPath()", () => {
+    test("converts Git Bash paths", () => {
+      if (process.platform === "win32") {
+        expect(Filesystem.windowsPath("/c/Users/test")).toBe("C:/Users/test")
+        expect(Filesystem.windowsPath("/d/dev/project")).toBe("D:/dev/project")
+      } else {
+        expect(Filesystem.windowsPath("/c/Users/test")).toBe("/c/Users/test")
+      }
+    })
+
+    test("converts Cygwin paths", () => {
+      if (process.platform === "win32") {
+        expect(Filesystem.windowsPath("/cygdrive/c/Users/test")).toBe("C:/Users/test")
+        expect(Filesystem.windowsPath("/cygdrive/x/dev/project")).toBe("X:/dev/project")
+      } else {
+        expect(Filesystem.windowsPath("/cygdrive/c/Users/test")).toBe("/cygdrive/c/Users/test")
+      }
+    })
+
+    test("converts WSL paths", () => {
+      if (process.platform === "win32") {
+        expect(Filesystem.windowsPath("/mnt/c/Users/test")).toBe("C:/Users/test")
+        expect(Filesystem.windowsPath("/mnt/z/dev/project")).toBe("Z:/dev/project")
+      } else {
+        expect(Filesystem.windowsPath("/mnt/c/Users/test")).toBe("/mnt/c/Users/test")
+      }
+    })
+
+    test("ignores normal Windows paths", () => {
+      expect(Filesystem.windowsPath("C:/Users/test")).toBe("C:/Users/test")
+      expect(Filesystem.windowsPath("D:\\dev\\project")).toBe("D:\\dev\\project")
+    })
+  })
+
   describe("writeStream()", () => {
     test("writes from Web ReadableStream", async () => {
       await using tmp = await tmpdir()