Add orbita theme

[salomaoparkour]

Theme submission

Adds orbita, a dark LinkStack theme with a switchable glass card, bevelled glass buttons, an animated living constellation, and customizable touch shockwaves.

• Source: https://github.com/salomaoparkour/linkstack-orbita-theme
• Release: https://github.com/salomaoparkour/linkstack-orbita-theme/releases/tag/v1.3.2
• Preview: https://raw.githubusercontent.com/salomaoparkour/linkstack-orbita-theme/main/preview.png
• LinkStack download: https://t.linkstack.org/?salomaoparkour/linkstack-orbita-theme

Checks

• Current public release is tagged v1.3.2
• Theme is dark mode and requires JavaScript
• Preview is a 1920 x 1080 PNG with the default card enabled
• Release archive is below the 2 MB limit
• The real LinkStack .button-entrance wrappers and staggered delays were included in the tests
• During each delay, buttons stay hidden and displaced; after entry, every wrapper returns to transform: none and opacity: 1
• Button blur was measured at 0px, 3px, 13px, and 24px over the same frozen constellation frame with the card disabled
• Button saturation was measured at 100%, 165%, and 200% over the same frozen constellation frame
• Card states 1, 0.5, and 0, interaction states, reduced motion, mobile layout, and scrolling with 24 buttons were verified in Chrome
• Firefox desktop layout and computed filters were verified; the local automated compositor did not render backdrop-filter pixels
• themes.json parses successfully and was not changed for this release