Check landing spot is actually open space, not just clear of the iris

computeSafeLanding() pushed the arrival point along the entry
direction only until it cleared the destination's iris footprint - it
never checked whether that spot was solid ground. A gate built close
to a wall (e.g. inside a room/temple) could push the landing straight
into that wall, embedding the player in it - which incidentally let
them walk out through the wall instead of a door, since they're
already clipped partway through it.

Now checks feet AND head height at each step for solid blocks while
searching forward (up to 8 blocks), stopping at the first spot that's
both clear of the iris and open space. Falls back to the furthest
wall-clear point found if nothing satisfies both within range, rather
than the original blind offset.

README.md

@@ -80,7 +80,10 @@ material, unsealed interior, too far from the sign, etc.
 - Travel is **one-way**: only the gate you dialed *from* can send anything anywhere.
   Walking (or wandering, or drifting) into its event horizon teleports whatever
   entered to the destination, arriving just clear of its iris (never inside it) and
-  still facing whatever direction it was already moving, so entering forward always
+  clear of any wall too - if the gate sits close to a wall (built inside a room, say),
+  the plugin checks the landing spot is actually open space and searches forward
+  along the entry direction for one instead of embedding the arrival in solid block.
+  It still faces whatever direction it was already moving, so entering forward always
   means exiting forward. The destination's horizon is visible but not walkable -
   stepping into it does nothing, same as a real Stargate only running one direction
   at a time.