Adding a button for copying error messages (#1882)

close #1870 





<!-- This is an auto-generated description by cubic. -->
---
## Summary by cubic
Adds a “Copy” button to error banners and chat error output so users can
quickly copy error messages with clear feedback. Addresses Linear #1870.

- **New Features**
- Introduced CopyErrorMessage component that writes to clipboard and
shows “Copied” for 2s.
- Added the copy button to the Preview error banner and DyadOutput;
actions grouped at the bottom beside “Fix with AI”.
- Added Playwright e2e test and helpers to verify copy behavior and
clipboard content.

<sup>Written for commit 12e9bf1437ded36dc022e1d795025580d2ffd111.
Summary will update automatically on new commits.</sup>

<!-- End of auto-generated description by cubic. -->

e2e-tests/snapshots/fix_error.spec.ts_fix-all-errors-button-1.aria.yml

@@ -7,11 +7,12 @@
 - img
 - text: "src/pages/Index.tsx Summary: intentionally add first error"
 - img
-- text: Error
+- text: Error First error in Index...
+- img
+- button "Copy":
+  - img
 - button "Fix with AI":
   - img
-- text: First error in Index...
-- img
 - img
 - text: ErrorComponent.tsx
 - button "Edit":
@@ -19,11 +20,12 @@
 - img
 - text: "src/components/ErrorComponent.tsx Summary: intentionally add second error"
 - img
-- text: Error
+- text: Error Second error in ErrorComponent...
+- img
+- button "Copy":
+  - img
 - button "Fix with AI":
   - img
-- text: Second error in ErrorComponent...
-- img
 - img
 - text: helper.ts
 - button "Edit":
@@ -31,11 +33,12 @@
 - img
 - text: "src/utils/helper.ts Summary: intentionally add third error"
 - img
-- text: Error
+- text: Error Third error in helper...
+- img
+- button "Copy":
+  - img
 - button "Fix with AI":
   - img
-- text: Third error in helper...
-- img
 - button "Fix All Errors (3)":
   - img
 - button: