Replace REST with gRPC on server

Switch from HTTP/1.1 protobuf-over-REST to gRPC over HTTP/2,
implemented directly on hyper without tonic. The gRPC framing
module handles encode/decode of the 5-byte length-prefixed wire
format, status codes, and HTTP/2 trailers.

Key changes:
- hyper http1 → http2, add TokioExecutor for HTTP/2 connections
- TLS ALPN set to h2 for HTTP/2 negotiation
- HMAC auth simplified to timestamp-only (no body) since TLS
  guarantees integrity
- Events delivered via tokio broadcast channel, replacing the
  RabbitMQ EventPublisher infrastructure
- Config renamed rest_service_addr → grpc_service_addr
- Removed lapin, async-trait, events-rabbitmq feature

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: benthecarman

ldk-server/Cargo.toml

@@ -6,10 +6,10 @@ edition = "2021"
 [dependencies]
 ldk-node = { git = "https://github.com/lightningdevkit/ldk-node", rev = "3aef2b39265ae60b29f4d60de8291895f12eb880" }
 serde = { version = "1.0.203", default-features = false, features = ["derive"] }
-hyper = { version = "1", default-features = false, features = ["server", "http1"] }
+hyper = { version = "1", default-features = false, features = ["server", "http2"] }
 http-body-util = { version = "0.1", default-features = false }
-hyper-util = { version = "0.1", default-features = false, features = ["server-graceful"] }
-tokio = { version = "1.38.0", default-features = false, features = ["time", "signal", "rt-multi-thread"] }
+hyper-util = { version = "0.1", default-features = false, features = ["server-graceful", "tokio"] }
+tokio = { version = "1.38.0", default-features = false, features = ["time", "signal", "rt-multi-thread", "sync"] }
 tokio-rustls = { version = "0.26", default-features = false, features = ["ring"] }
 ring = { version = "0.17", default-features = false }
 getrandom = { version = "0.2", default-features = false }
@@ -18,25 +18,17 @@ ldk-server-grpc = { path = "../ldk-server-grpc" }
 bytes = { version = "1.4.0", default-features = false }
 hex = { package = "hex-conservative", version = "0.2.1", default-features = false }
 rusqlite = { version = "0.31.0", features = ["bundled"] }
-async-trait = { version = "0.1.85", default-features = false }
 toml = { version = "0.8.9", default-features = false, features = ["parse"] }
 chrono = { version = "0.4", default-features = false, features = ["clock"] }
 log = "0.4.28"
 base64 = { version = "0.21", default-features = false, features = ["std"] }
 clap = { version = "4.0.5", default-features = false, features = ["derive", "std", "error-context", "suggestions", "help", "env"] }
 
-# Required for RabittMQ based EventPublisher. Only enabled for `events-rabbitmq` feature.
-lapin = { version = "2.4.0", features = ["rustls"], default-features = false, optional = true }
-
 [features]
 default = []
-events-rabbitmq = ["dep:lapin"]
 
 # Experimental Features.
 experimental-lsps2-support = []
 
-# Feature-flags related to integration tests.
-integration-tests-events-rabbitmq = ["events-rabbitmq"]
-
 [dev-dependencies]
 futures-util = "0.3.31"

ldk-server/ldk-server-config.toml

@@ -3,7 +3,7 @@
 network = "regtest"                           # Bitcoin network to use
 listening_addresses = ["localhost:3001"]      # Lightning node listening addresses
 announcement_addresses = ["54.3.7.81:3001"]   # Lightning node announcement addresses
-#rest_service_address = "127.0.0.1:3536"       # LDK Server REST address (optional, defaults to 127.0.0.1:3536)
+#grpc_service_address = "127.0.0.1:3536"       # LDK Server gRPC address (optional, defaults to 127.0.0.1:3536)
 alias = "ldk_server"                          # Lightning node alias
 #pathfinding_scores_source_url = ""           # External Pathfinding Scores Source
 #rgs_server_url = "https://rapidsync.lightningdevkit.org/snapshot/v2/"  # Optional: RGS URL for rapid gossip sync
@@ -38,11 +38,6 @@ server_url = "ssl://electrum.blockstream.info:50002"  # Electrum endpoint
 [esplora]
 server_url = "https://mempool.space/api"      # Esplora endpoint
 
-# RabbitMQ settings (only required if using events-rabbitmq feature)
-[rabbitmq]
-connection_string = ""                        # RabbitMQ connection string
-exchange_name = ""
-
 # LSPS2 Client Support
 [liquidity.lsps2_client]
 # The public key of the LSPS2 LSP we source just-in-time liquidity from.