Plan the artist platform: price calculator and fan-funded pressing

New docs/artist-platform.md: upload master and artwork with automatic
audio, artwork and rights checks; an itemised price calculator for every
customer (per-title vs per-copy lines, price-per-copy curve, lead time
from the production-timeline quote table, versioned price list); and
fan-funded campaigns that press and dropship per fan once the goal is
reached, refund otherwise. Covers goal maths, payments (charge into a
ring-fenced account, CNX as seller of record, legal opinion first; the
Qrates failure as the design rule), repress pre-orders, architecture on
the cnx-factory stack with the public side on a fleet machine, PDPA,
phasing (calculator public early as a run-size probe, campaigns only
after first releases ship), cost and open decisions.

Backlinks from README, process flow, production timeline, revenue model,
digital factory and roadmap items 1 and 20; total investment added-scope
table gains the platform line.

README.md

@@ -109,6 +109,11 @@ The detail lives in dedicated documents:
 - [Process flow](docs/process-flow.md): the whole chain from audio file to
   delivered record as a chart and stage table, with every check and the
   three artist approval gates (printable diagram alongside)
+- [Artist platform](docs/artist-platform.md): upload a master and
+  artwork, get a transparent itemised offer from the price calculator
+  (for artists, labels and any other customer), and optionally launch a
+  fan-funded campaign that the plant presses and ships to each fan once
+  enough have pre-ordered, with refunds if not
 - [Plant operation page](docs/plant-operation.html): a single static page
   animating the whole plant as a simulated SCADA overview, from PVC intake
   and the material lab through extruder, press, trim, optical inspection,
@@ -155,6 +160,7 @@ docs/
 ├── finance/               Project cost overviews, revenue model,
 │                          construction RFQ
 ├── suppliers/             Supplier contacts, vendor landscape, supplier map
+├── artist-platform.md     Upload, price calculator, fan-funded pressing
 ├── biomass.md             Biomass fuel strategy and the 60 rai coppice idea
 ├── boi.md                 BOI promotion strategy and requirements
 ├── crane-workshop-tours.md Overhead crane, workshop, visitor corridor