docs: company logo, stamp & brand bar on exported POs

Document the new Company.logoKey/stampKey branding fields, the company-assets
storage namespace, and how logo/stamp/brand-bar render on PO exports.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Data-Model.md

@@ -128,10 +128,12 @@ Only **leaf** accounts (no children) are PO-selectable. Seed data:
 
 ### Company — multi-company invoicing
 `name, code? (unique, e.g. PMS), gstNumber?, address?, telephone?, mobile?,
-email?, invoiceEmail?, invoiceAddress?, isActive`. The sister company a PO is
-billed under (`PurchaseOrder.companyId`, optional); its details populate the
-**exported PO header / invoice block** (falling back to Pelagia defaults).
-Managed at `/admin/companies`.
+email?, invoiceEmail?, invoiceAddress?, logoKey?, stampKey?, isActive`. The
+sister company a PO is billed under (`PurchaseOrder.companyId`, optional); its
+details populate the **exported PO header / invoice block** (falling back to
+Pelagia defaults). `logoKey`/`stampKey` are storage keys for the branding
+images shown on exported POs (see [File Storage](File-Storage)). Managed at
+`/admin/companies`.
 
 ### Vendor + VendorContact
 `Vendor`: `name, vendorId? (unique formal code), address?, pincode?, gstin?,

File-Storage.md

@@ -47,9 +47,17 @@ production**.
   (`@unique poId`), upserted on repeat confirmations (notes preserved).
 - **Approval signature** (`User.signatureKey`) — uploaded by approvers from the
   profile page; appears on exported PO documents.
+- **Company branding** (`Company.logoKey`, `Company.stampKey`) — a logo and a
+  stamp/seal uploaded per company from **Admin → Companies → Edit → Branding**
+  (permission `manage_vessels_accounts`). Keys are deterministic
+  (`company-assets/<companyId>/{logo,stamp}.<ext>`) so a re-upload overwrites in
+  place. Both appear on exported POs — logo top-left, stamp in the approver's
+  signatory block. Upload via the `uploadCompanyAsset` server action (≤ 4 MB,
+  PNG/JPG/WebP), not the presigned-URL flow.
 
 Client-side upload is helped by `lib/upload-files.ts`. The export endpoint embeds
-the approver's signature in the generated PDF/XLSX.
+the approver's signature, the company logo and stamp, and a fixed-colour brand
+bar at the bottom of the generated PDF/XLSX.
 
 ## Required env (production)
 

Purchase-Orders.md

@@ -106,6 +106,13 @@ approved, not creation).
 approver's name (and uploaded signature) appears as signatory; company details
 populate the header; optional line-item descriptions are included.
 
+**Company branding** (set per company in Admin → Companies → Edit → Branding)
+also renders on the export: the uploaded **logo** floats top-left of the header,
+the uploaded **stamp/seal** overlays the approver's signatory block, and a fixed
+brand-colour bar (`#92D050`) runs full-width along the bottom. Each piece is
+optional except the bar, which is always drawn. See
+[File Storage](File-Storage#where-files-attach).
+
 ## Import PO → CLOSED
 
 `/po/import` parses a Pelagia-format Excel PO (`lib/po-import-parser.ts`,