feat: add interactive hinge hero

[janicduplessis]

Description

The Hinges landing illustration was static, so it could not show how hinge angle relates to posture. This adds an illustrative, user-controlled fold while keeping it separate from native device readings. It also adds a prominent link to the existing Reanimated integration guide.

Closes #15.

Solution

The range control updates the two screen halves, displayed radians, and illustrative posture together. Labels stay readable and reduced motion disables transitions. The Reanimated link makes the optional native shared-value integration discoverable without promising a delivery rate or frame rate.

Test plan

• Built the production Docusaurus site.
• In a browser, changed the slider to 0.20 rad and confirmed the halves folded around the hinge with the closed illustrative posture.
• Focused the slider and pressed Right Arrow; the visible value changed to 0.21 rad.