update sample app

cfg/sample/soleprint/atlas/books/fixture/index.md

@@ -1,44 +0,0 @@
-# Fixture Invoicing — Soleprint Demo
-
-> **This book describes a deliberately-fake invoicing app used as a test
-> fixture for the Soleprint framework.** It is not a real product.
-
-## Purpose
-
-The fixture exercises every soleprint tool end-to-end so we can iterate on
-the framework without needing a real managed app. See
-[`examples/fixture-invoicing/`](../../../../../../examples/fixture-invoicing/)
-for the app itself.
-
-## Data model
-
-```
-Customer ──< Invoice ──< LineItem
-              └──────< Payment
-```
-
-| Table       | Key fields                                      |
-|-------------|-------------------------------------------------|
-| `customer`  | id · name · email · created_at                  |
-| `invoice`   | id · number · customer_id · issued_at · status  |
-| `line_item` | id · invoice_id · description · qty · unit_price|
-| `payment`   | id · invoice_id · amount · method · paid_at     |
-
-## Happy-path flow
-
-1. Create a customer (`POST /api/customers`)
-2. Create a draft invoice for them (`POST /api/invoices`)
-3. Add one or more line items (`POST /api/line-items/invoices/{id}`)
-4. Record a payment (`POST /api/payments/invoices/{id}`) — if the total
-   paid ≥ total billed, the invoice auto-transitions to `paid`.
-
-## How this connects to Soleprint
-
-| Soleprint tool | Fixture hook |
-|----------------|--------------|
-| datagen        | `station/tools/datagen/fixture.py` — FixtureInvoicingGenerator |
-| graphgen       | `station/tools/graphgen/schema.json` — 4 models + FK edges    |
-| databrowse     | `station/tools/databrowse/depot/{schema,views}.json`          |
-| tester         | `station/tools/tester/tests/fixture/`                         |
-| link           | SQLAlchemy reflection against `customer`, `invoice`, etc.     |
-| sbwrapper      | Injected into fixture's Vue frontend by nginx                 |