Aerie and flying creatures: bats, chain gargoyles, arcane owls, ember wyrms

- New room: aerie (key Y, rooms category, campaign from mission 7); flyers sleep there
- Arrivals: aerie 4+ bats; + torture chamber gargoyles; + library owls; big aerie and treasury
  (16+ each) a rare ember wyrm; portal checks free places in lairs and aerie separately
- Flyers cross water and lava (path finding, flag, attacks), are not burnt by lava, patrol far
  when idle, attack single enemies, flee to the aerie below 25% health and rest there up to 75%
- Owls shoot arcane bolts, the wyrm breathes fire with splash damage; shots from the air
- Hovering sprites with flapping, aerie floor, perches, roosts, plinths, twig and ember nests
- Room counts are recounted on load (no longer stored); tests for flying and arrivals

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

lang/en.lang

@@ -146,7 +146,7 @@ help.k_slap = Shift+Left      Hand: backhand own units, punch heroes on your gro
 help.k_pan = Right drag      Move the map (also WASD/arrows, screen edge)
 help.k_rot = Middle drag     Rotate and tilt the camera (also Q/E, R/F)
 help.k_zoom = Mouse wheel     Zoom
-help.k_tools = 1-9,0,X,V,K,J,B,C,T,U  Select tool
+help.k_tools = 1-9,0,X,V,K,J,B,C,T,U,Y  Select tool
 help.k_misc = P / Space       Pause      M  Sound on/off   +/-  Volume
 help.k_misc2 = G               Tile outlines on/off     H  This help
 help.s1 = 1. Dig to the portal and let your Pit Imps claim it.
@@ -518,3 +518,13 @@ rank.7 = Master Sergeant
 rank.8 = Captain
 rank.9 = Colonel
 rank.10 = Warlord
+
+# aerie and flying creatures
+tool.aerie.label = Aerie
+tool.aerie.desc = Perches and nests for flying creatures. 4+ tiles attract giant bats; with a torture chamber chain gargoyles, with a library arcane owls; a big aerie (16+) and treasury (16+) may lure an ember wyrm. Flyers cross water and lava.
+room.aerie = Aerie
+unit.bat = Giant Bat
+unit.gargoyle = Chain Gargoyle
+unit.owl = Arcane Owl
+unit.wyrm = Ember Wyrm
+job.rest = Recovering in the aerie