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/build.rs

@@ -144,11 +144,13 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     let proto_files = [
         "src/proto/error.proto",
         "src/proto/tests.proto",
-        "src/proto/cli.proto",
+        "src/proto/api_instance.proto",
+        "src/proto/api_logger.proto",
+        "src/proto/api_config.proto",
+        "src/proto/api_manage.proto",
         "src/proto/web.proto",
         "src/proto/magic_dns.proto",
         "src/proto/acl.proto",
-        "src/proto/config.proto",
     ];
 
     for proto_file in proto_files.iter().chain(proto_files_reflect.iter()) {
@@ -161,7 +163,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
         .type_attribute(".acl", "#[derive(serde::Serialize, serde::Deserialize)]")
         .type_attribute(".common", "#[derive(serde::Serialize, serde::Deserialize)]")
         .type_attribute(".error", "#[derive(serde::Serialize, serde::Deserialize)]")
-        .type_attribute(".cli", "#[derive(serde::Serialize, serde::Deserialize)]")
+        .type_attribute(".api", "#[derive(serde::Serialize, serde::Deserialize)]")
         .type_attribute(".web", "#[derive(serde::Serialize, serde::Deserialize)]")
         .type_attribute(".config", "#[derive(serde::Serialize, serde::Deserialize)]")
         .type_attribute(
@@ -180,7 +182,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
             "#[derive(Hash, Eq, serde::Serialize, serde::Deserialize)]",
         )
         .type_attribute("common.RpcDescriptor", "#[derive(Hash, Eq)]")
-        .field_attribute(".web.NetworkConfig", "#[serde(default)]")
+        .field_attribute(".api.manage.NetworkConfig", "#[serde(default)]")
         .service_generator(Box::new(rpc_build::ServiceGenerator::new()))
         .btree_map(["."])
         .skip_debug([".common.Ipv4Addr", ".common.Ipv6Addr", ".common.UUID"]);