README banner: the logo above the STEWARD wordmark

scripts/banner.py builds artwork/banner.svg from the web UI's logo and
wordmark, as Jarl's does; scripts/logo.py runs it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

scripts/logo.py

@@ -8,13 +8,15 @@
 #                                        logo appears together with the page
 #
 # The master is hand-written SVG: <g> elements whose attributes apply to
-# their <path> and <circle> children. Run from the repository root after
-# changing it:
+# their <path> and <circle> children. It then runs scripts/banner.py to
+# rebuild the README's banner. Run from the repository root after changing
+# it:
 #
 #   python3 scripts/logo.py
 import json
 import os
 import shutil
+import subprocess
 import sys
 import xml.etree.ElementTree as ET
 
@@ -51,6 +53,7 @@ def main():
     shutil.copyfile(MASTER, os.path.join(OUT, "logo.svg"))
     for name in ("logo.svg", "logo.js"):
         print(f"{OUT}/{name}: {os.path.getsize(os.path.join(OUT, name))} bytes")
+    subprocess.run([sys.executable, "scripts/banner.py"], check=True)
 
 
 if __name__ == "__main__":