Add the entities.png manifest, paste-in template and sprite loader

The sheet becomes a fixed grid (one row per entity, one column slot per
animation state) described by a sidecar entities.toml that only maps
names to rows; the loader reads present states and frame counts off the
pixels, so assembling the sheet by hand needs no bookkeeping.
tools/mktemplate.py renders the labelled template with low-alpha slot
guides. The CGA atlas is kept for larger UI text.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

assets/tilesets/entities.toml

@@ -0,0 +1,116 @@
+# Sidecar manifest for entities.png.
+#
+# The sheet is a grid of 8×8 cells: one entity per row, one fixed column slot per
+# state. States are Idle, Sit, Walk, Action 1, Action 2, Hit, Dead; a slot holds up to
+# `max` frames, left to right. Frames present in a slot are detected from the PNG
+# (a fully transparent cell ends the animation, an empty slot means the entity has no
+# such state and Idle is shown instead) — so this file only says WHERE things are,
+# never how many frames exist.
+#
+# `assets/tilesets/entities-template.png` (from `tools/mktemplate.py`) shows the
+# same layout with labels and slot guides: paste sprites into it, save it as
+# entities.png. The label column and header are outside `origin` and never loaded.
+
+[layout]
+cell   = 8
+origin = [64, 16]   # x, y of the first sprite cell (right of the labels, below the header)
+
+# state = [first column (cells, relative to origin), max frames]
+[layout.states]
+idle    = [0, 2]
+sit     = [2, 2]
+walk    = [4, 4]
+action1 = [8, 4]
+action2 = [12, 2]
+hit     = [14, 2]
+dead    = [16, 2]
+
+# name = row (0-based). Order is free, rows must be unique.
+[entities]
+player        = 0
+
+ghost1        = 1
+ghost2        = 2
+mutant_rat    = 3
+slime1        = 4
+slime2        = 5
+slime3        = 6
+ent           = 7
+shroom        = 8
+floating_eye  = 9
+
+chick         = 10
+hen           = 11
+rooster       = 12
+fox_kit       = 13
+fox           = 14
+rabbit_kit    = 15
+rabbit        = 16
+mouse_pup     = 17
+mouse         = 18
+kitten1       = 19
+cat1          = 20
+kitten2       = 21
+cat2          = 22
+puppy         = 23
+dog           = 24
+foal1         = 25
+horse1        = 26
+foal2         = 27
+horse2        = 28
+foal3         = 29
+horse3        = 30
+foal4         = 31
+horse4        = 32
+
+baby_bird1    = 33
+bird1         = 34
+baby_bird2    = 35
+bird2         = 36
+cardinal_chick = 37
+cardinal      = 38
+baby_eagle    = 39
+eagle         = 40
+baby_crow     = 41
+crow          = 42
+
+piglet        = 43
+pig           = 44
+calf          = 45
+cattle        = 46
+kid           = 47
+goat          = 48
+lamb          = 49
+sheep         = 50
+duckling      = 51
+duck          = 52
+wolf_pup      = 53
+wolf          = 54
+doe           = 55
+buck          = 56
+boar_piglet   = 57
+boar          = 58
+bear_cub      = 59
+bear          = 60
+squirrel_kit  = 61
+squirrel      = 62
+turkey_chick  = 63
+turkey        = 64
+opossum_joey  = 65
+opossum       = 66
+skunk_kit     = 67
+skunk         = 68
+raccoon_cub   = 69
+raccoon       = 70
+
+fish1         = 71
+fish2         = 72
+fish3         = 73
+fish4         = 74
+bees          = 75
+bugs1         = 76
+bugs2         = 77
+butterfly1    = 78
+butterfly2    = 79
+butterfly3    = 80
+butterfly4    = 81