Art: emit the palette as .gpl/.ase/.aco as well as .act

The .act files only helped Photoshop. Affinity imports .ase and .aco;
Inkscape, GIMP, Krita and Aseprite want .gpl. tools/make_palettes.py now
generates all four plus swatch PNGs, for both the full 16 and the
11-colour portrait subset, all derived from the same PALETTE table shared
with kissaten.c so nothing can drift.

Colour names ride along in .gpl/.ase/.aco, so the swatches show up labelled
("skin", "lamp glow", "dusk violet") rather than as anonymous chips.

.ase output verified by reading it back and checking all 11 colours
round-trip exactly.

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

projects/kissaten_yugure/art/kissaten-portrait.gpl

@@ -0,0 +1,15 @@
+GIMP Palette
+Name: Kissaten Yugure (portrait)
+Columns: 11
+#
+ 36  36  36	outline
+ 73  36  36	dark wood
+146  73  36	mid wood
+182 109  73	light wood
+255 182  73	lamp glow
+255 219 146	cream
+109  73  73	muted wall
+109  36   0	coffee
+ 73 109 182	coat blue
+255 182 146	skin
+255 255 219	warm white