Art tooltips: "Verbessert durch" lists what improves each art

Arts are objects (game::Art) built from the game's definitions: name,
launch type, damage source, regeneration group and the skills' art lists.
The tooltip gets one line per effect of a skill or attribute, sorted by
size; unlearned class skills are greyed out at 0%. Weapon arts list only
the damage types the held weapon deals and the held weapon's skill.
Tooltip line wrap ignores colour codes; art tooltips wrap wider.
Blitzschlag's tooltip rewrite becomes a tooltip filter.

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

CMakeLists.txt

@@ -38,6 +38,7 @@ add_library(sacred_re SHARED
     src/game/engine/items.cpp
     src/game/engine/stream.cpp
     src/game/ui/texts.cpp
+    src/game/engine/art.cpp
     src/mods/borderless.cpp
     src/mods/widescreen.cpp
     src/mods/hud.cpp
@@ -58,6 +59,7 @@ add_library(sacred_re SHARED
     src/mods/combos.cpp
     src/mods/aurahits.cpp
     src/mods/chainlightning.cpp
+    src/mods/arttooltip.cpp
     src/mods/escape.cpp
     src/mods/recordcache.cpp
     src/mods/megamap.cpp