feat: Improve Public URL Readability (#2482)

* added support for group slugs

* modified frontend to use links with group slug

* fixed test refs

* unused import

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Co-authored-by: Hayden <64056131+hay-kot@users.noreply.github.com>

mealie/schema/user/user.py

@@ -181,6 +181,7 @@ class PrivateUser(UserOut):
 class UpdateGroup(GroupBase):
     id: UUID4
     name: str
+    slug: str
     categories: list[CategoryBase] | None = []
 
     webhooks: list[Any] = []