chore: keep the logo generator in the repository

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

scripts/brand/README.md

@@ -0,0 +1,15 @@
+# The LambdaMail mark
+
+The logo is a lambda drawn as two straight strokes of one weight, each end cut
+square to the baseline, joined without a seam, on a flat ultramarine tile with
+continuous (superelliptic) corners. It is deliberately flat and has no rounded
+strokes: it has to hold at 16 pixels and on both themes.
+
+`mark.py` holds the geometry. Change a number there, never the SVG by hand.
+
+    python3 scripts/brand/mark.py        # writes icon.svg and the logo-*.svg files
+    CHROME_PATH=/path/to/chrome node scripts/brand/icons.mjs   # renders the PNGs and favicon.ico
+
+`icons.mjs` needs `puppeteer-core` and a Chrome. The inline copy of the mark in
+`services/webmail/src/components/Logo.tsx` carries the same two paths: after a
+change, paste the `glyph:` line `mark.py` prints into `LAMBDA`.