Tenant public branding (background color & header image)

Restaurant owners can customise the look of public-facing pages (book a table, customer menu, reservation view) with:

Background colour — Hex colour for the page background (e.g. #1E22AA for RAL5002 Azul). Set in Settings → Business profile via colour picker, hex input, or the RAL5002 (Azul) preset.
Header background image — Image shown behind the hero header (logo and restaurant name). Upload in Settings → Business profile; JPG, PNG, WebP or AVIF; same size/optimisation as logo. Remove via the ✕ button (calls DELETE /tenant/header-background).

Where it applies

When a header image is set, a dark overlay keeps text readable.

Model: Tenant.public_background_color (VARCHAR, hex), Tenant.header_background_filename (stored under uploads/{tenant_id}/header/).
Migrations: 20260319100000_add_tenant_public_background_color.sql, 20260319110000_add_tenant_header_background.sql.
Endpoints: GET /uploads/{tenant_id}/header/{filename} (serve image), POST /tenant/header-background (upload), DELETE /tenant/header-background (remove). Logo (business profile): POST /tenant/logo, DELETE /tenant/logo (remove file and clear logo_filename). Public tenant and menu responses include public_background_color and header_background_filename / tenant_header_background_filename.

Settings: Business profile tab: “Public site background color” (colour + hex + RAL5002 preset), “Header background image” (upload + remove).
Public pages: Root container gets [style.--color-bg] when colour is set; hero header gets [style.background-image] and class has-bg-image when header image is set (with overlay in SCSS).