Add the haunted house wallpaper

[vaprdev]

A crooked Victorian haunted house as the centerpiece, in a dead forest above a graveyard, under a huge moon.

• Calm: flickering candle and pumpkins, creeping fog, a raven turning its head, glowing eyes in the woods. Lively: bats from the turret, ghosts, a peeking ghoul, a hooded reaper, a spider on its thread. Teeming: a lurching zombie, a hand clawing out of a grave, a witch across the moon, a light moving room to room.
• Clicks show a figure in a window, pop up a ghoul or burst out bats; a finished agent sends the witch past; errors bring lightning; the easter egg is a zombie dance.

Verified: typecheck, build, dev/check.ts haunted-house in octant and quadrant modes and --verify-dirty (0 failed), screenshots up to date.