Make /introduction the single "What is HyperFrames?" page a stranger can be
sent, and retire the switchboard that sat in front of it.
- introduction: lead with one sentence + a sound-on result (drop `muted`),
simplify the loop diagram to request -> agent -> project -> video, cut the
fake "See how it works" scroll button, and replace the equal-weight card
walls with one clear "Start here" action.
- guides/index: remove the six-card "What do you need to do?" menu-of-menus.
The nav already routes people and /introduction is the real entry point.
Redirect /guides -> /introduction.
- developers: point the "create a video" link at /quickstart.
mint validate and mint broken-links both pass.
ukimsanov