feat(po): add MCP server, agent-friendly PO API, and PDF rendering
- server/pb-mcp.mjs: 15-tool MCP server for purchase-order workflow
(CRUD, suppliers, stock, customers, customer POs, validate_draft,
generate_order_number)
- src/lib/api/purchaseOrders.ts: typed helpers shared by UI + MCP + n8n
- src/components/purchase-orders/pdf.ts: jsPDF PO generator
- src/components/purchase-orders/ViewOrderDialog.tsx: read-only dialog
- src/components/purchase-orders/AttachmentsDialog.tsx: attachment mgmt
- src/components/purchase-orders/NumberInput.tsx: numeric input
- scripts/mcp-create-po.mjs: end-to-end driver (MCP stdio smoke test)
- pocketbase/pb_migrations/1786200007_*: schema migration
- docs/MCP_AND_N8N.md: MCP + n8n integration guide
Verified end-to-end via MCP: generate_order_number → create_purchase_order
with snapshot_items for an actual quote (DRILL-19042 / 161053).