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_002_Walk.png.import

@@ -0,0 +1,40 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://bris5vy0xmie6"
+path="res://.godot/imported/Character_002_Walk.png-2734f78de0275bc238cdbc3320fddda0.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://art/sprites/characters/Character_002_Walk.png"
+dest_files=["res://.godot/imported/Character_002_Walk.png-2734f78de0275bc238cdbc3320fddda0.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/uastc_level=0
+compress/rdo_quality_loss=0.0
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/channel_remap/red=0
+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1