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.

docs/finance/revenue-model.md

@@ -381,6 +381,10 @@ effectively unavailable in Thailand. That floor exists because per-title
 cost — an imported stamper set plus outsourced mastering — is irreducible
 for them. In-house cutting and plating collapses it, which makes short
 runs viable for CNX in a way they structurally are not for ResurRec.
+The channel planned for that segment is the
+[artist platform](../artist-platform.md): a transparent price calculator
+and fan-funded campaigns that press only when enough fans have
+pre-ordered.
 
 **What it does to the volume-versus-boutique question.** The model assumes
 1.0–1.5M records/yr across 300–600 titles, an average of 1,700–5,000 units