assets/favicon.svg — 4-point sparkle star in acid green on a rounded dark
square. Scales cleanly at any size (16px tab icon through Retina). Uses the
Silent Mode palette so it recognisably reads as Silent Mode family.
assets/logo.svg — the same star + "sirius.x" wordmark with the .x accented in
acid green. Used as the og:image; can also be inlined as a brand mark.
Every page (landing / docs / portal / theseus) gets:
* <link rel="icon"> + <link rel="mask-icon"> pointing at favicon.svg
* og:type, og:site_name, og:title, og:description, og:url, og:image
* twitter:card + twitter:title/description on the landing (summary card)
Absolute paths (/sirius-x/assets/…) so subpages get the same brand mark
without per-page path juggling.
