buildNpmPackage is built into nixpkgs and pre-fetches dependencies as a
fixed-output derivation with network access. npmDepsHash is a
placeholder (lib.fakeHash) — the first build will fail with a hash
mismatch that reports the correct hash.
npm ci in buildPhase hangs because the Nix build sandbox has no network
access. Adopt nix-bitcoin's approach: fetchNodeModules pre-fetches
node_modules as a fixed-output derivation (which has network access),
and the main build copies them offline. Uses the same node_modules hash
as upstream nix-bitcoin for RTL 0.15.8.
- Create packages/rtl/default.nix to build RTL from source
- Update modules/bitcoin/rtl.nix to use vendored package instead of pkgs.rtl
- Remove clightning/lightning-loop references (Sovran is LND-only)
- Simplify to LND-only configuration
