Skills, auto-attack, aura and chain lightning rework, Esc, cache fix

- Skill bar: no art selection; slot 0 is the right-click art, keys 0-6 cast
  slots directly; cooldown labels in exact seconds; slot 0 set apart.
- Arts regenerate on their own (casting no longer refills the group).
- Auto-attack after targeting or casting at a hostile creature, at the speed
  of a held button.
- Auras can be recast while active (renew, no second visual).
- Blicke wie Klingen hits every enemy in range, physical, with life leech.
- Blitzschlag steers the game's own chain: 3 + level/5 hits, 1 + level/10
  chains, re-hits a lone enemy.
- Weapon sets: click selects, drag only from the selected set; the leftmost
  set is clickable (signed hit tests).
- Esc closes open windows before opening the game menu.
- HUD: standalone buttons and texts are centred.
- Record cache sized for widened views (town lag while walking).
- Shared game code: orders, fx events, text drawing, cooldowns, effects.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

CMakeLists.txt

@@ -32,6 +32,8 @@ add_library(sacred_re SHARED
     src/game/engine/log.cpp
     src/game/engine/cmdline.cpp
     src/game/engine/events.cpp
+    src/game/engine/fx.cpp
+    src/game/engine/orders.cpp
     src/mods/borderless.cpp
     src/mods/widescreen.cpp
     src/mods/hud.cpp
@@ -43,6 +45,13 @@ add_library(sacred_re SHARED
     src/mods/skillbar.cpp
     src/mods/arttarget.cpp
     src/mods/aura_restore.cpp
+    src/mods/autoattack.cpp
+    src/mods/aurarecast.cpp
+    src/mods/artregen.cpp
+    src/mods/aurahits.cpp
+    src/mods/chainlightning.cpp
+    src/mods/escape.cpp
+    src/mods/recordcache.cpp
 )
 target_include_directories(sacred_re PRIVATE src)
 target_compile_options(sacred_re PRIVATE ${SACRED_RE_CXX_FLAGS})