[feature] Add support of Preview Cards

[kaimanhub]

Description

Purpose of the code change is to add support of Preview Cards for status with links.

closes #1345

Checklist

• I/we have read the GoToSocial contribution guidelines.
• I/we have discussed the proposed changes already, either in an issue on the repository, or in the Matrix chat.
• I/we have not leveraged AI to create the proposed changes.
• I/we have performed a self-review of added code.
• I/we have written code that is legible and maintainable by others.
• I/we have commented the added code, particularly in hard-to-understand areas.
• I/we have made any necessary changes to documentation.
• I/we have added tests that cover new code.
• I/we have run tests and they pass locally with the changes.
• I/we have run go fmt ./... and golangci-lint run.

[tsmethurst]

Hiya, thanks for opening! Will get to reviewing this properly when time permits, but one thing I immediately see when taking a quick look through the code is that you're using go's http standard library to do HTTP calls. Instead of doing this, you should use our transportcontroller to fetch an http client that you can then use to make the call. That client uses our custom http client logic, including range limiting and some other tweaks (proper user-agent, etc).