HUD pass, weapon and trinket rework, and font arrows

HUD:
- Hotbars fit a quarter of the screen, dropping to small then tiny slots
  (thinner outlines when tiny), with cooldown bars matching their size.
- HUD elements are drawn on their own layer and composited at one
  opacity: hotbar slots are see-through until hovered, the rest fade
  while hovered.
- Rival windows fit the right column in at most two rows, shrinking
  icons then font, then dropping icons for name, health and ping bars.
- Tooltips number equipped items' slots and say Recoil for weapons that
  only push back. Previews use arrows, spread uses degrees.
- Crosshair fills in and shakes with charge, and weapons shake after
  firing until their cooldown ends. DPS and speed meters off by default.

Gameplay:
- Dual Wield stacks: each copy fires another recently held weapon from
  a fanned off-hand, at its own level's cut.
- Flamethrower: no slowing, smaller fireball with some recoil, and an
  airblast that knocks others away.
- Iron Weights slam on any landing faster than a plain fall (platforms
  too), stacking radius and damage, and speeding fast falls.
- Stuck arrows are one-way ledges until they fade, matching their
  (slightly larger) hit size. Attacks now collide with slopes.
- Halved Tesla Coil, Recoil Coil, Diazepam, Shock Absorber, Feather and
  screenshake values.

Art and tools:
- Weapon and trinket icons merged into one sheet each (normal, small,
  tiny), cells in catalog order. Grimoire wisps stand upright.
- Fonts gain the degree sign and four arrows, decoded from UTF-8.
- Menu fighter preview walks at quarter speed.
- Unequip from either catalog tab by right click or gamepad.

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

resources/font/huge.fnt

@@ -98,6 +98,11 @@
     "{": {"x": 374, "y": 215, "w": 33, "h": 42, "dx": -3, "dy": 0, "advance": 15},
     "|": {"x": 408, "y": 215, "w": 33, "h": 42, "dx": -3, "dy": 0, "advance": 9},
     "}": {"x": 442, "y": 215, "w": 33, "h": 42, "dx": -3, "dy": 0, "advance": 15},
-    "~": {"x": 476, "y": 215, "w": 33, "h": 42, "dx": -3, "dy": 0, "advance": 21}
+    "~": {"x": 476, "y": 215, "w": 33, "h": 42, "dx": -3, "dy": 0, "advance": 21},
+    "°": {"x": 510, "y": 215, "w": 33, "h": 42, "dx": -3, "dy": 0, "advance": 15},
+    "←": {"x": 0, "y": 258, "w": 33, "h": 42, "dx": -3, "dy": 0, "advance": 21},
+    "↑": {"x": 34, "y": 258, "w": 33, "h": 42, "dx": -3, "dy": 0, "advance": 21},
+    "→": {"x": 68, "y": 258, "w": 33, "h": 42, "dx": -3, "dy": 0, "advance": 21},
+    "↓": {"x": 102, "y": 258, "w": 33, "h": 42, "dx": -3, "dy": 0, "advance": 21}
   }
 }