feat: allow building a catalogue before Stripe is configured

[jsnapoli1]

Problem

Creating a product with no STRIPE_SECRET_KEY set fails with a 500:

{"error":"Neither apiKey nor config.authenticator provided","status":500}

POST /api/admin/products syncs to Stripe before writing to KV, and new Stripe(undefined) throws on construction. So a store cannot be stocked, previewed, or demoed until payment credentials exist — even though building a catalogue usually comes first, and Stripe onboarding (business details, bank account) can take days.

Approach

StripeService already had the mechanism for this in isLocalNoNetwork, which skips remote sync and returns stub ids while KV writes continue. It was gated to a dev-only sentinel. This generalises it to "no key configured" via a skipsRemoteSync getter, then adds what's needed to make it safe on a live store.

Product writes degrade; payments do not. That asymmetry is the core of the design — a store that silently accepted uncharged orders would be worse than one that fails to start.

Changes

• Product create/update/archive and price create/archive no-op when unconfigured, writing placeholder ids (prod_unlinked, price_unlinked).
• Both checkout paths refuse with 503 This store is not accepting payments yet. There is no account to charge, and the placeholder ids don't exist in Stripe.
• GET /api/payments-status reports whether payments are live, so a storefront can hide Buy buttons. Exposes only presence, never the key.
• The admin panel shows a banner in catalogue-only mode.
• Backfill: saving an unlinked product once a key is configured creates it in Stripe rather than updating an id that never existed there, and writes the real ids back to KV.
• validateEnv no longer requires STRIPE_SECRET_KEY, which otherwise reports a store as invalid when it's merely not selling yet.
• Documented in docs/STRIPE.md.

Verification

Tests — adds tests/integration/catalogue-only.test.js (5 cases: status reporting both ways, product create without Stripe, checkout refusal, backfill-on-save).

Test Files  24 passed (24)
     Tests  283 passed (283)

npm run lint — 0 errors (10 pre-existing warnings in untouched files). npm run harness:docs passes.

Live Cloudflare Workers deployment, no STRIPE_SECRET_KEY set:

GET  /api/payments-status        → {"paymentsEnabled":false}
POST /api/admin/products         → 201  (previously 500)
                                   stripeProductId: "prod_unlinked"
POST /api/create-checkout-session → 503  {"error":"This store is not accepting payments yet."}

Notes

The sk_test_local_no_network sentinel keeps its existing behaviour and its distinct log message; catalogue-only mode is a separate condition that happens to share the skip path.

Depends on nothing, but stacks cleanly with #84 (unrelated admin crash fix).

https://claude.ai/code/session_015XLFFfHWNeazSuz6UcsQ4C