Starry Sky – Interactive Night Sky Cover Block

Starry Sky adds a container block that behaves like the core Cover block — you
can nest any blocks on top of it (headings, paragraphs, buttons, etc.) — but
instead of a background image it paints a realistic night sky on an HTML canvas:

• Hundreds of stars with varied sizes, brightness, and true stellar colours
  (blue-white, white, warm, orange, and red), rendered with a soft glow.
• Diffraction “sparkle” spikes on the brightest stars.
• Gentle twinkling.
• Mouse interaction: the whole field parallaxes with the pointer (nearer stars
  move more), and stars near the cursor are pushed away and spring back — a
  push-and-pull that follows the mouse.
• Click the sky to launch a shooting star from that point.
• Occasional shooting stars drift by on their own, at a rate you set
  (shooting stars per minute; 0 to turn them off).

Settings (block sidebar):

• Minimum height
• Star density
• React to mouse movement (on/off)
• Twinkle (on/off)
• Shooting star on click (on/off)
• Shooting stars per minute (0–30; 0 = off)
• Sky colour
• Vertical alignment of the overlaid content (toolbar)

Accessibility & performance:

• Respects prefers-reduced-motion (renders a static sky, no animation or
  pointer reaction).
• Uses pre-baked sprites and pauses rendering while the block is off-screen.