etcp_router: Ed25519 digital signature for service messages

- Add ed25519_public_key[32] to NODEINFO struct for pubkey distribution
- Add ed25519_public_key[32] to ROUTE_BGP (derived from X25519 privkey at init)
- Add ROUTER_FLAG_SIGNED (0x08) to SVC_ROUTE_HDR flags byte
- router_send_one_flags: when is_signed, sign [hdr][payload] and append 64-byte sig
- etcp_router_recv_cb: verify Ed25519 signature when ROUTER_FLAG_SIGNED set
- New API: etcp_router_conn_send_signed()
- Drop signed packets if sender node not in routing table or no Ed25519 key
- 5 unit tests in test_etcp_router_unit.c covering OK/tampered/unknown/no-key/short

src/config_parser.c

@@ -386,6 +386,9 @@ static int parse_global(const char *key, const char *value, struct global_config
     if (strcmp(key, "log_file") == 0) {
         return assign_string(global->log_file, sizeof(global->log_file), value);
     }
+    if (strcmp(key, "db_path") == 0) {
+        return assign_string(global->db_path, sizeof(global->db_path), value);
+    }
     /* debug_categories key is deprecated - use [debug] section instead */
     if (strcmp(key, "enable_timestamp") == 0) {
         global->enable_timestamp = atoi(value);
@@ -407,7 +410,7 @@ static int parse_global(const char *key, const char *value, struct global_config
         global->tun_test_mode = atoi(value);
         return 0;
     }
-    DEBUG_ERROR(DEBUG_CATEGORY_CONFIG, "%s:%d: Unknown global option '%s'. Valid: my_node_name, my_private_key, my_public_key, my_node_id, tun_ifname, tun_ip, mtu, keepalive_timeout, keepalive_interval, bbr_max_cwnd, debug_level, log_file, enable_timestamp, enable_function_names, enable_file_lines, enable_colors, tun_test_mode", filename, line_num, key);
+    DEBUG_ERROR(DEBUG_CATEGORY_CONFIG, "%s:%d: Unknown global option '%s'. Valid: my_node_name, my_private_key, my_public_key, my_node_id, tun_ifname, tun_ip, mtu, keepalive_timeout, keepalive_interval, bbr_max_cwnd, debug_level, log_file, db_path, enable_timestamp, enable_function_names, enable_file_lines, enable_colors, tun_test_mode", filename, line_num, key);
     return -1;
 }