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/auto-attack.md

@@ -0,0 +1,54 @@
+# Auto-attack (`src/mods/autoattack.cpp`)
+
+Goal (user, 2026-10-15): once an enemy was targeted, by a left click or by
+casting an art at it, the hero keeps attacking it with the weapon between
+casts. Left click stays the normal attack; right click casts slot 0.
+
+## What the game does (order log, 2026-10-15)
+
+Orders logged in `cCreature::ReceiveOrder` (`0x52e400`) for the hero, with
+the hero's fields per tick:
+
+| Order | Caller | Fields |
+|---|---|---|
+| left click on an enemy: `cmd 7` | `0x617abb` | +0x18 target id, +0x1c / +0x20 its position |
+| art: `cmd 0x105` | `0x6172f9` (`SendCreatureOrder`) | +0x10 target id, +0x18 / +0x1c ground point, +0x28 0x64, +0x2c 1, +0x30 art id |
+| walk: `cmd 4` | `0x6172f9` | see docs/wasd.md |
+| hit by an enemy: `cmd 5` | `0x4ea478` | +0x8 attacker id, +0x10 the hero, +0x2c 1.0f (every ~0.5 s) |
+
+One left click is one swing: hero +0x150 goes 0x10000 (idle) -> 0x10003
+(attack) -> 0x20003 -> 0x10000 within about a second; +0xfc 0 -> 4 ->
+0x20004 -> 0 at the start. An art: 0x10001 -> 0x10008 -> 0x20008 -> 0 ->
+0x10000. Low word of +0x150: current action (0 none, 1 art, 3 attack, 6
+dying), high word its phase. `cCreature::IsAlive` (`0x548ef0`): +0xfc != 9,
++0x150 != 6, health +0x4d8 != 0.
+
+Holding the left button on an enemy (measured): one attack order, then +0x150
+stays 0x10003 for as long as the button is held (9 s in the test), no further
+orders. At the end of each swing (after the hit, `0x4e6584`) the attack code
+calls `cMouseCursor::IsButtonHeld` (`0x655ab0`, cursor word bit 8) at
+`0x4e65c6` (attacker in esi, target creature in ebp; measured: the only
+caller answered "held" during a held attack): held -> the next swing starts
+right away, otherwise recovery (+0x152 = 2) and idle. (`0x4f665a`, a similar
+check in another creature update, is not reached by the hero.) Re-sending
+the attack order after the hero went idle took ~1.45 s per swing (0.36 s
+wind-up, 0.64 s attack, 0.43 s recovery).
+
+## The mod
+
+- An attack order or an art order whose target is hostile
+  (`cCreature::IsHostileTo` `0x548dd0`, faction relation) sets the combat
+  target. (First version: "not an ally", which included NPCs: clicking a
+  trader made auto-attack talk to it again and again, reopening its window
+  with new stock.) any walk order (mouse, WASD, stop) clears it, as
+  does the target's death.
+- Each engine tick, if the hero is idle (+0x150 low word 0), no mouse button
+  is held (engine +0x54 & 0x10), input is not blocked (0x4000) and no skill
+  key is held, it sends the attack order a left click sends. After sending it
+  waits up to 5 ticks for the swing to start.
+- The end-of-swing button check (`call` at `0x4e65c6`) is redirected: it
+  also answers "held" when the hero hits its auto-attack target, the target
+  is alive and no skill key is held. Swings then chain like
+  with a held button; the tick only restarts the attack after casts.
+- Self / ally arts pointed at an enemy lose their target
+  (`src/mods/arttarget.cpp`) and therefore do not start auto-attack.