perf: reduce binary sizes from 15M/11M to 3.8M/5.5M

- Add [profile.release]: opt-level=z, lto=true, strip=true, codegen-units=1, panic=abort
- Replace vendored openssl (~5MB) with ed25519-dalek (pure Rust, ~100KB)
- Feature-gate deps: server (actix, chrono) vs pusher (zmq, reqwest, ed25519-dalek)
- Remove unused confy dependency
- bal-pusher: 15M -> 3.8M (-75%)
- bal-server: 11M -> 5.5M (-50%)

src/bin/bal-pusher.rs

@@ -6,6 +6,7 @@ use bitcoincore_rpc::{Auth, Client, Error, RpcApi, bitcoin};
 use bitcoincore_rpc_json::GetBlockchainInfoResult;
 
 use byteorder::{LittleEndian, ReadBytesExt};
+use ed25519_dalek::{Signer as _, SigningKey, pkcs8::DecodePrivateKey};
 use log::{debug, error, info, trace, warn};
 use serde::Deserialize;
 use serde::Serialize;
@@ -22,10 +23,7 @@ use zmq::{Context, DEALER, DONTWAIT, Socket};
 use bal_server::db::open_db;
 use bal_server::validation::is_valid_welist_url;
 use base64::{Engine as _, engine::general_purpose};
-use openssl::pkey::PKey;
-use openssl::sign::Signer;
 use reqwest::Client as rClient;
-use std::fs;
 use std::net::SocketAddr;
 use std::time::Instant;
 use url::Url;
@@ -558,14 +556,11 @@ async fn send_stats_report(
     Ok(())
 }
 fn sign_message(private_key_path: &str, message: &str) -> String {
-    let key_data = fs::read(private_key_path).unwrap();
+    let signing_key =
+        SigningKey::read_pkcs8_pem_file(private_key_path).expect("failed to parse private key PEM");
+    let signature = signing_key.sign(message.as_bytes());
 
-    let private_key = PKey::private_key_from_pem(&key_data).unwrap();
-    let mut signer = Signer::new_without_digest(&private_key).unwrap();
-
-    let signature = signer.sign_oneshot_to_vec(message.as_bytes()).unwrap();
-
-    general_purpose::STANDARD.encode(&signature)
+    general_purpose::STANDARD.encode(signature.to_bytes())
 }
 
 fn parse_env(cfg: &mut MyConfig) {