refactor(rpc): Centralize RPC service and unify API (#1427)

This change introduces a major refactoring of the RPC service layer to improve modularity, unify the API, and simplify the overall architecture.

Key changes:
- Replaced per-network-instance RPC services with a single global RPC server, reducing resource usage and simplifying management.
- All clients (CLI, Web UI, etc.) now interact with EasyTier core through a unified RPC entrypoint, enabling consistent authentication and control.
- RPC implementation logic has been moved to `easytier/src/rpc_service/` and organized by functionality (e.g., `instance_manage.rs`, `peer_manage.rs`, `config.rs`) for better maintainability.
- Standardized Protobuf API definitions under `easytier/src/proto/` with an `api_` prefix (e.g., `cli.proto` → `api_instance.proto`) to provide a consistent interface.
- CLI commands now require explicit `--instance-id` or `--instance-name` when multiple network instances are running; the parameter is optional when only one instance exists.

BREAKING CHANGE:  
RPC portal configuration (`rpc_portal` and `rpc_portal_whitelist`) has been removed from per-instance configs and the Web UI. The RPC listen address must now be specified globally via the `--rpc-portal` command-line flag or the `ET_RPC_PORTAL` environment variable, as there is only one RPC service for the entire application.

easytier/src/utils.rs

@@ -10,7 +10,7 @@ use crate::common::{
     config::LoggingConfigLoader, get_logger_timer_rfc3339, tracing_rolling_appender::*,
 };
 
-pub type PeerRoutePair = crate::proto::cli::PeerRoutePair;
+pub type PeerRoutePair = crate::proto::api::instance::PeerRoutePair;
 
 pub fn cost_to_str(cost: i32) -> String {
     if cost == 1 {
@@ -30,7 +30,7 @@ pub fn init_logger(
     config: impl LoggingConfigLoader,
     need_reload: bool,
 ) -> Result<Option<NewFilterSender>, anyhow::Error> {
-    use crate::instance::logger_rpc_service::{CURRENT_LOG_LEVEL, LOGGER_LEVEL_SENDER};
+    use crate::rpc_service::logger::{CURRENT_LOG_LEVEL, LOGGER_LEVEL_SENDER};
 
     let file_config = config.get_file_logger_config();
     let file_level = file_config
@@ -254,6 +254,11 @@ pub fn find_free_tcp_port(mut range: std::ops::Range<u16>) -> Option<u16> {
     range.find(|&port| check_tcp_available(port))
 }
 
+pub fn weak_upgrade<T>(weak: &std::sync::Weak<T>) -> anyhow::Result<std::sync::Arc<T>> {
+    weak.upgrade()
+        .ok_or_else(|| anyhow::anyhow!("{} not available", std::any::type_name::<T>()))
+}
+
 #[cfg(test)]
 mod tests {
     use crate::common::config::{self};