feat(spine): build Spine in as a 2D skeletal animation solution (4.2 backend)

e2e/.dev/public/spineboy.atlas

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+spineboy.png
+	size: 1024, 256
+	filter: Linear, Linear
+	scale: 0.5
+crosshair
+	bounds: 352, 7, 45, 45
+eye-indifferent
+	bounds: 862, 105, 47, 45
+eye-surprised
+	bounds: 505, 79, 47, 45
+front-bracer
+	bounds: 826, 66, 29, 40
+front-fist-closed
+	bounds: 786, 65, 38, 41
+front-fist-open
+	bounds: 710, 51, 43, 44
+	rotate: 90
+front-foot
+	bounds: 210, 6, 63, 35
+front-shin
+	bounds: 665, 128, 41, 92
+	rotate: 90
+front-thigh
+	bounds: 2, 2, 23, 56
+	rotate: 90
+front-upper-arm
+	bounds: 250, 205, 23, 49
+goggles
+	bounds: 665, 171, 131, 83
+gun
+	bounds: 798, 152, 105, 102
+head
+	bounds: 2, 27, 136, 149
+hoverboard-board
+	bounds: 2, 178, 246, 76
+hoverboard-thruster
+	bounds: 722, 96, 30, 32
+	rotate: 90
+hoverglow-small
+	bounds: 275, 81, 137, 38
+mouth-grind
+	bounds: 614, 97, 47, 30
+mouth-oooo
+	bounds: 612, 65, 47, 30
+mouth-smile
+	bounds: 661, 64, 47, 30
+muzzle-glow
+	bounds: 382, 54, 25, 25
+muzzle-ring
+	bounds: 275, 54, 25, 105
+	rotate: 90
+muzzle01
+	bounds: 911, 95, 67, 40
+	rotate: 90
+muzzle02
+	bounds: 792, 108, 68, 42
+muzzle03
+	bounds: 956, 171, 83, 53
+	rotate: 90
+muzzle04
+	bounds: 275, 7, 75, 45
+muzzle05
+	bounds: 140, 3, 68, 38
+neck
+	bounds: 250, 182, 18, 21
+portal-bg
+	bounds: 140, 43, 133, 133
+portal-flare1
+	bounds: 554, 65, 56, 30
+portal-flare2
+	bounds: 759, 112, 57, 31
+	rotate: 90
+portal-flare3
+	bounds: 554, 97, 58, 30
+portal-shade
+	bounds: 275, 121, 133, 133
+portal-streaks1
+	bounds: 410, 126, 126, 128
+portal-streaks2
+	bounds: 538, 129, 125, 125
+rear-bracer
+	bounds: 857, 67, 28, 36
+rear-foot
+	bounds: 663, 96, 57, 30
+rear-shin
+	bounds: 414, 86, 38, 89
+	rotate: 90
+rear-thigh
+	bounds: 756, 63, 28, 47
+rear-upper-arm
+	bounds: 60, 5, 20, 44
+	rotate: 90
+torso
+	bounds: 905, 164, 49, 90