Add Z.AI to the list of sites with invalid manifests

Author: filips123

docs/docs/resources/specific-website-tips.md

@@ -41,3 +41,4 @@ of a bug in PWAsForFirefox, please create a new issue.
 | [Old Reddit](https://old.reddit.com/)     | Reddit's manifest contains `shortcuts` items that use relative URLs. According [to the manifest specification](https://w3c.github.io/manifest/#processing-shortcut-items), shortcut URLs should be parsed with the manifest URL as the base URL, and the resulting URL should be within the scope (which is determined based on the document URL). Because the manifest is located on a different domain than the main website, shortcuts will be parsed with the wrong URL as a base and fail the required checks. As a workaround, install Reddit without the manifest enabled or use the new Reddit design. | [#61](https://github.com/filips123/PWAsForFirefox/issues/61), [#485](https://github.com/filips123/PWAsForFirefox/issues/485) |
 | [Google Tasks](https://tasks.google.com/) | Google Tasks' manifest is restricted behind login, so the native program cannot access it. As a workaround, install Google Tasks without the manifest enabled.                                                                                                                                                                                                                                                                                                                                                                                                                                                 | [#714](https://github.com/filips123/PWAsForFirefox/issues/714)                                                               |
 | [Twitter/X](https://x.com/)               | Twitter's manifest contains `screenshots` and `shortcuts` items that do not provide image URLs. As a workaround, install Twitter without the manifest enabled.                                                                                                                                                                                                                                                                                                                                                                                                                                                 | [#724](https://github.com/filips123/PWAsForFirefox/issues/724)                                                               |
+| [Z.AI](https://chat.z.ai/)                | Z.AI's manifest is served on a different domain and specifies a start URL relative to the manifest URL. As a result, the start URL is resolved to a different domain than the main document, which fails the required checks. As a workaround, install Z.AI without the manifest enabled.                                                                                                                                                                                                                                                                                                                      | [#792](https://github.com/filips123/PWAsForFirefox/issues/792)                                                               |