Add Homepage and Repository fields to manifests

[Dekkonot]

Supersedes #180. Making a new PR because it's hard to repair that one after the work done on the site recently.

Closes #183.

[magnalite]

LGTM!

Tiny nitpick - The repo text can run off the edge of the webpage. (I don't think it is worth caring about right now unless the fix is trivial. Just eliding the link if it is too long is probably fine.)

[Dekkonot]

So, looking into fixing this: the link gets truncated on desktop too, since it's too long for the column:

Even trimming off the scheme of the URL like crates.io doesn't work, as our text is too large. If we drop it down a few points though, it's perfectly fine with the scheme cut off:

This does add a bit more work but it's probably worth it to ensure it looks okay?

[cloudflare-workers-and-pages]

Deploying wally-registry-frontend with    Cloudflare Pages

Latest commit:	11e3a9a
Status:	✅  Deploy successful!
Preview URL:	https://60ab0acb.wally-registry-frontend.pages.dev
Branch Preview URL:	https://test.wally-registry-frontend.pages.dev

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