Mirrors the layout from data/mail_template.png:
- Company name + greeting headline
- Body referencing the invoice number
- Inline logo (cid:invoice-logo) attached automatically
- Footer with mailto + website links
New template vars: {{shopEmail}}, {{shopWebsite}}.
Settings UI prefills empty fields with the defaults so users see and
can tweak them without losing the fallback.
Vite/React Router refused to bundle the client because
app/routes/app.settings.tsx imported the constant from a .server file
and used it inside the route component (not just loader/action), so it
could not be tree-shaken out.
Move the sentinel to logoCache.constants.ts, re-export from
logoCache.server.ts for backwards compatibility, and import the constant
from constants in the route while keeping the server-only functions
(deleteStoredLogo, storeUploadedLogo) imported from .server (they are
only referenced inside the action and get tree-shaken correctly).
Gerhard Scheikl