[BUG] Card button has issues: `button-label` not implemented and not following alignment

[giggio]

Describe the bug

If you use button-label as explained in the docs it does not show the label.

Also, align is not being applied to the label.

To reproduce

Steps to reproduce the behavior:

1. Create a card with button-label set to some text and set button to true and set alignment to center

Expected behavior

Button shows set label and is center aligned.

Log file

N/A.

Screenshots

N/A.

Host environment

• Hinode version: v1.6.3
• Host OS: Ubuntu 24.04
• Node version: 24.1.0
• Browser: [Brave 1.79.119 (Official Build) (64-bit)](https://brave.com/latest/) | Chromium: 137.0.7151.68

Hugo environment

hugo v0.147.7+extended+withdeploy linux/amd64 BuildDate=unknown VendorInfo=nixpkgs
GOOS="linux"
GOARCH="amd64"
GOVERSION="go1.24.3"
github.com/sass/libsass="3.6.6"
github.com/webmproject/libwebp="v1.3.2"

Additional context

N/A.