Lightning Stream 0.2.1 for StartOS

Lightning Stream 0.2.1 for StartOS.

A fix to 0.2.0.

• On Browse, Found on Nostr, a shop reached by its key (such as the demo shop, Lightning Stream
  Genesis) now offers Add this shop. Its list is signed by the key that is its address, so it is the
  shop's own. Before, it offered only Check with the seller, which asks the seller's web address; a
  shop reached by its key has none, so the check failed with a name-lookup error. Adding the shop by its
  key under Sellers worked all along.
• A file that costs less than a shop's smallest ticket can be bought. A Download, or a file opened
  in your player, now lets its first call buy one whole ticket (546 sat, 559 with routing fees, at the
  least) even when the file costs less, such as Big Buck Bunny at Lightning Stream Genesis (about 284
  sat). What the file doesn't use stays as credit with the shop. Before, the call's limit was the
  file's own price, so a buyer with no credit got a raw JSON refusal and nothing was paid. Where the
  wallet names a larger smallest ticket (up to 2,000 sat), the call is made once more with it, and any
  other refusal is now a page in words. Your spending rules still apply to every payment.
• A web-app visit needs a limit of at least 559 sat. A smaller limit opened a visit whose first
  request said the limit was reached with nothing spent. The form now refuses it, says why, and sets
  the limit to 559 sat for you to confirm; what a visit doesn't use stays as credit with the shop.

It moves real funds on mainnet and has been tested there with small amounts only. Start with low limits.

What you need first

• StartOS 0.4.0.2 or later.
• Knots BLAKE2b, the node for the Bitcoin BLAKE2b chain.
• Lightning Fork 0.21.4-beta.21.1:2 or later, from its StartOS registry, https://start9.paulscode.com/, with a channel.

Install from the Lightning Stream registry, https://registry.lazarus-xbt.xyz (Marketplace → Switch → Add). StartOS then shows updates as they come; earlier installs update in place. Or sideload the .s9pk for your server (x86_64 or aarch64) under System → Sideload a service. The step-by-step guide is docs/STARTOS.md.

Connecting your Lightning node: Lightning Stream asks Lightning Fork for its own key. Run Lightning Fork's Grant app access task for Lightning Stream to approve it; nothing to paste. The key can only pay, within your spending rules, and you can revoke it in Lightning Fork at any time. Selling needs two invoice-only keys that you make in Lightning Fork and paste on the Sell page, for now.

SHA256SUMS lists the files' checksums.