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>

docs/performance.md

@@ -0,0 +1,20 @@
+# Performance
+
+## Record cache in widened views (`src/mods/recordcache.cpp`)
+
+Measured 2026-10-15 (Battlemage save in a town, frame time at Flip, sampling
+profiler over all threads): walking took 90-130 ms per frame in the widened
+view, 17 ms with widescreen off; idle 17 ms in both.
+
+The render thread spent most samples in a std::map walk (0x832b80 /
+0x832ba0, called from 0x636222) inside FUN_006360e0: a record-by-id cache
+(map at +0xde5c, size at +0xde60, 16-byte value at node +0x14, last-used
+stamp at node +0x24 from 0xcd59d0; misses read the record from the file at
++0x23c). With 4096 entries or more, every insert walks the whole map to
+erase the single least recently used entry. The widened view needs more
+records than that, so walking evicted and reloaded constantly.
+
+Fix: the limit (`cmp ecx, 1000h` at 0x636201) is raised to 0x8000 so the
+per-insert walk never runs; before a lookup with 0x6000 entries the mod
+erases the less recently used half in one pass (map::erase 0x63da10). Walking
+in town: 17 ms per frame again (confirmed by the user).