docs(email): document IMPORT structure + literal-hex brand constraint

email/README.md

@@ -46,18 +46,24 @@ them to users on various events (password reset, digest, ban, etc.).
 
 ## Partials
 
-`partials/` holds fragments included by the templates above:
+`partials/` holds fragments imported by the templates above. Every
+non-partial template starts with `<!-- IMPORT emails/partials/header.html -->`
+and ends with `<!-- IMPORT emails/partials/footer.html -->`.
 
 - `header.html` — shared email head/header markup.
 - `footer.html` — shared footer with the unsubscribe block
   (`{{{ if showUnsubscribe }}}`).
-- `post-queue-body.html` — renders a queued post (category, topic, author,
-  content) inside `notification.html` for post-queue notifications.
+- `post-queue-body.html` — queued-post notification body fragment (category,
+  topic, author, content), maintained for use by a notification branch/template.
 
 ## Editing notes
 
 - These are emails: inline CSS, table layout, MSO/Outlook conditional
   comments. Keep that structure — don't refactor into modern CSS.
+- Brand colors are literal inline hex because Outlook/Gmail strip `var()`.
+  `scss/westgate/_tokens.scss` holds the source values but is not available at
+  runtime; keep the dark letterhead band + light cream card pattern. Preheader
+  copy lives in `languages/en-GB/email.json`.
 - Don't hardcode user-facing copy; add/replace `[[email:…]]` keys and define
   them in the language files.
 - Run `node scripts/check-emails.js` after converting templates. It enforces