Generate and check-in icons

Checking in icons is not super pretty git practice, but when rendering
through GitHub, that's the easiest option

.icons/app.png.license

@@ -0,0 +1,3 @@
+SPDX-License-Identifier: CC-BY-3.0
+SPDX-License-CopyrightText: delapouite
+Original file from https://game-icons.net/1x1/delapouite/keyboard.html

.icons/board.png.license

@@ -0,0 +1,3 @@
+SPDX-License-Identifier: CC-BY-3.0
+SPDX-License-CopyrightText: lorc
+Original file from https://game-icons.net/1x1/lorc/circuitry.html

.icons/rebuild.py

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+#!/usr/bin/env python3
+# SPDX-License-Identifier: CC0-1.0
+# SPDX-FileCopyrightText: chrysn <[email protected]>
+# /// script
+# dependencies = ["cairosvg"]
+# ///
+
+import urllib.request
+import cairosvg
+
+game_icons = {
+        "board": ("lorc", "circuitry"),
+        "app": ("delapouite", "keyboard"),
+        }
+
+for (outname, (author, iconname)) in game_icons.items():
+    svg = urllib.request.urlopen(f"https://game-icons.net/icons/ffffff/000000/1x1/{author}/{iconname}.svg").read()
+    outname = outname + ".png"
+    cairosvg.svg2png(bytestring=svg, write_to=outname, output_width=20, output_height=20)
+    with open(outname + ".license", "w") as licensefile:
+        print("SPDX-License-Identifier: CC-BY-3.0", file=licensefile)
+        print(f"SPDX-License-CopyrightText: {author}", file=licensefile)
+        print(f"Original file from https://game-icons.net/1x1/{author}/{iconname}.html", file=licensefile)