chore: keep the logo generator in the repository

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

.wolf/cerebrum.md

@@ -30,6 +30,7 @@ budget_tokens: 2000
 - [2026-10-22] `services/protocols` e2e tests apply only migration 0001. Delivery code must not call SQL functions or columns from later migrations.
 - [2026-10-22] A `<Button>` inside a `<form>` submits it unless `type="button"` (Undo send used to resend the message).
 - [2026-10-22] Never run side effects inside a React state updater (it can run twice).
+- [2026-10-23] Inside a JS template literal `\\d` silently becomes `d`. For scripts embedded in template strings write `[0-9]` instead of `\\d`, and test the script's behaviour, not only that it is present.
 
 ## Decision Log
 
@@ -38,3 +39,5 @@ budget_tokens: 2000
 - 2026-10-22 Trusted senders live in table `trusted_senders`; delivery rescues a Junk verdict only when DMARC passed, or SPF passed for the From domain (a forged From must not be rescued).
 - 2026-10-22 Conversations: `thread_id` is written at delivery (Message-ID, then In-Reply-To/References, then Re:-subject); NULL means "its own conversation" via COALESCE(thread_id, id). Subject key is computed in Go at delivery and in SQL (`lm_subject_key`) for the backfill; a test holds them equal.
 - 2026-10-22 Themes: every colour is a CSS variable per theme (`globals.css`), Tailwind scales (slate, indigo, amber, rose, emerald) read them, `ink` is the on-ground colour. Dark is default; the theme is chosen by a script in `<head>` before first paint. Font Geist is self-hosted (@fontsource-variable/geist).
+- 2026-10-23 Logo: a lambda of two straight strokes of one weight, ends cut square, joined without a seam, flat ultramarine tile with continuous corners. The first version (round caps, gradient, envelope flap) read as childish; do not go back to round-capped strokes. Generator: `scripts/brand/` (mark.py, icons.mjs); `Logo.tsx` carries the same path.
+- 2026-10-23 Reader: a message written plainly is drawn in the app's colours (transparent frame, text lifted if too dark, white backdrops cleared); a designed one (backgrounds, bgcolor, 3+ tables) keeps a white sheet. Decided by `looksDesigned` in `lib/emailBody.ts`; a reply's quoted history folds behind a button.