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/hud.md

@@ -58,3 +58,15 @@ copying and writing back hold the real object's lock).
 A primitive drawn inside a moved window that covers the whole 1024x768 layout
 (e.g. the dimming behind the exit confirmation) is stretched across the render
 width instead of shifted.
+
+## Standalone controls (quest dialog)
+
+Some dialogs (e.g. accepting a quest) are not one of the hooked window
+classes: their buttons and texts sit directly in the UI manager as top-level
+controls (measured: the clicked button's root window was the cUI_Button2
+itself). They were drawn unshifted or with whichever window's scope happened
+to be active, so the dialog jumped between the 1024 layout and the centre and
+clicks only hit at the unshifted position. `cUI_Button2`, `cUI_Static2`,
+`cUI_StaticText64`, `cUI_StaticText64FX` (render and event) and
+`cUI_TextLines` (render) are hooked as centred windows too; inside other
+windows they are in that window's scope already (outermost wins).