Allow previews to open readable files (#1214)

* Allow previews to open readable files

* Fix Windows file preview path test

* Address file preview review comments

packages/app/src/utils/assistant-image-source.test.ts

@@ -53,6 +53,19 @@ describe("resolveAssistantImageSource", () => {
     });
   });
 
+  it("uses the same home-root target as file previews for tilde paths", () => {
+    expect(
+      resolveAssistantImageSource({
+        source: "~/.paseo/screenshots/output.png",
+        workspaceRoot: "/Users/test/project",
+      }),
+    ).toEqual({
+      kind: "file_rpc",
+      cwd: "~",
+      path: "~/.paseo/screenshots/output.png",
+    });
+  });
+
   it("normalizes file URIs into file RPC requests", () => {
     expect(
       resolveAssistantImageSource({