Touch interface for phones and tablets; category toolbar for mouse and touch

- touch.rs: gesture recognition (tap, double tap, long press, drag, two-finger pan/pinch/rotate)
- Touch mode: Auto (touch device or first touch) / On / Off in Settings -> Game
- Larger interface factor on touch screens, top bar wraps, smaller minimap, fewer messages
- Toolbar grouped into categories with pop-up rows and a menu button, also on the desktop
- Long press shows information or drops held units; double tap with the hand slaps
- Savegame name via the browser's text dialog when the name field is tapped
- Touch help texts (EN/DE)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

DESIGN.md

@@ -65,6 +65,8 @@ An original dungeon management game (genre: dungeon building & defence) that run
 - Claim the **portal** → creatures: kobold, cave spider, shadow mage, stone ogre (depending on rooms)
 - **Needs**: sleep, food, wages (payday); unhappy creatures leave
 - **Hand**: left click picks up own units (max. 8) and unconscious heroes on own ground; right click drops them on own ground (prisoners onto a free torture place are locked up); Shift + left click slaps: backhand for own units (15 s +50% speed, −5% HP, a little mood, wakes sleepers), fist for heroes on own ground (15 damage, 1 s stun, 0.5 s cooldown)
+- **Toolbar by categories** (Dig, Hand, Rooms, Towers, Spells, Orders, Menu) for mouse and touch alike; categories with several tools open a row of tools
+- **Touch interface** (Auto / On / Off; auto = touch device or first touch): larger interface factor (about 2/3 of the device pixel ratio), top bar wraps onto several lines, gestures: tap = tool, drag = rectangle or pan, two fingers = pan / pinch zoom / twist rotate, long press = info or drop, double tap with the hand = slap; savegame names via the browser's text dialog
 - **Pixel-art mouse pointers**: pointing monster hand with the icon of the active tool; grabbing hand / fist for the hand tool; animated backhand and punch; the active tool is highlighted in the toolbar (pulsing frame and arrow)
 - **Spells** (mana): lightning, heal, summon Pit Imp
 - **Heroes**: knight, archer, priest, dwarf miner, paladin of light (they dig their way to the Soul Core)