[WIP] Document Invoice Management on Adobe Commerce Storefront

[loginesta]

Purpose of this pull request

Add public documentation for the order-centric invoice list and details containers in the Order drop-in. The pages cover order context, routing, loading/error states, PDF download and host-provided branding, and current data limitations.

Architecture decision for team confirmation: This documentation places OrderInvoices and InvoiceDetails under the existing Order drop-in, matching the current implementation. Please confirm this is the agreed direction before considering the decision complete.

Associated JIRA ticket

USF-4396

Staging preview

Not available yet. Adding the preview URL after the PR preview is deployed.

Affected pages

• Order overview
• Order Quick Start
• Order Containers overview
• OrderInvoices container
• InvoiceDetails container
• Order Functions
• Order initialization
• Order Data & Events
• Order Slots
• Order styles
• Order Dictionary

Links to source code and related tickets

• USF-4334: GraphQL query — customer order list (MVP) => https://github.com/adobe-commerce/storefront-order/pull/159
• USF-4252: Invoices navigation entry + page scaffold => https://github.com/adobe-commerce/storefront-order/pull/160
• USF-4257: GraphQL query + page — single invoice detail => https://github.com/adobe-commerce/storefront-order/pull/162 & USF-4257: Add AEM invoice details and navigation hlxsites/aem-boilerplate-commerce#1482
• USF-4259: PDF template — Luma layout + site logo => https://github.com/adobe-commerce/storefront-order/pull/163
• USF-4258: Invoice PDF download (individual) => https://github.com/adobe-commerce/storefront-order/pull/163

What's New highlights

• Added Order drop-in documentation for listing invoices associated with an order and viewing an individual invoice.
• Documented invoice routing, order context, loading/error states, and PDF download/branding options.
• Documented current API limitations, including unavailable invoice status and per-item tax data.