Pawn reskin Slice 1 — peasant sprites replace coloured disc

Pawns now render as AnimatedSprite2D children sourced from ElvGames
"Farming Characters Pack" atlases (Pack 1, characters 001-015). Each
pawn picks one of 15 peasants deterministically from name hash:
Bram=004, Cora=013, Edda=001.

Animations: idle_down/left/right/up + walk_down/left/right/up (4 fps
idle, 8 fps walk, looped) + dead (single frame, no loop). Pawn picks
animation each _process tick from (is_downed, is_walking, facing).
Facing is now a Vector2i field updated in _advance_walk; round-trips
through save/load.

Sprite mounting is deferred from _ready() to setup() / from_dict()
because the atlas pick depends on pawn_name, which isn't assigned at
_ready time.  _mount_sprite() is idempotent for the save-load chain.

_atlas_for_pawn(pawn) is the single Slice-2 extension point —
swapping atlases based on equipped armor in a future sprint is a
one-function change.

_draw() stripped of body disc + downed-rotation; now overlay-only
(selection ring + carry indicator). AnimatedSprite2D child uses
z_index=-1 so the overlays stay on top.

45 PNGs copied into art/sprites/characters/ + 45 .import companions.

art/sprites/characters/Character_008_Idle.png.import

@@ -0,0 +1,40 @@
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+path="res://.godot/imported/Character_008_Idle.png-3f55478f0d4f6dabc7b8b70c3d3a37cd.ctex"
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+"vram_texture": false
+}
+
+[deps]
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+dest_files=["res://.godot/imported/Character_008_Idle.png-3f55478f0d4f6dabc7b8b70c3d3a37cd.ctex"]
+
+[params]
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+compress/lossy_quality=0.7
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+compress/rdo_quality_loss=0.0
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+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
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+roughness/src_normal=""
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+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
+process/fix_alpha_border=true
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