Add basic product setup for MWP

[sigilabcodex]

This PR adds a narrow basic product/catalog confirmation path for MWP readiness.

Highlights:

• Upgrades the existing /admin/setup products area into a basic product confirmation/editor section
• Supports MWP product fields: name, default unit, optional category, active/inactive
• Adds catalog repository methods for product lookup/upsert
• Ensures new products have a default variant for order suggestions
• Clarifies in orders/order form that confirmed products are suggestions, while freeform lines remain allowed
• Updates the MWP readiness audit

Checks:

• npm run typecheck passed
• npm run build passed

Out of scope:

• No procurement/inventory
• No recipe/costing expansion
• No catalog redesign
• No variant system rewrite
• No route churn