feat(mini): add compact native EasyTier client (#2479)

Add a native EasyTier proof-of-concept binary with TCP and UDP
transports, TUN, UDP hole punching, AES-GCM, and a read-only RPC
portal.

Introduce a release-derived mini profile and musl linker policy so
x86_64, big-endian MIPS, and little-endian MIPS stay below the strict
5,000,000-byte target without UPX.

easytier-core/src/config/mod.rs

@@ -1,8 +1,8 @@
 //! Static configuration schema plus the live runtime configuration store.
 
-#[cfg(feature = "management")]
+#[cfg(feature = "web-client")]
 pub mod api;
-#[cfg(any(feature = "management", feature = "browser-config"))]
+#[cfg(any(feature = "web-client", feature = "browser-config"))]
 pub mod api_input;
 #[cfg(all(
     feature = "browser-config",

easytier-core/src/config/runtime.rs

@@ -95,6 +95,23 @@ impl CoreRuntimeConfigStore {
             .send_modify(|version| *version += 1);
     }
 
+    pub(crate) fn replace_with_current(
+        &self,
+        mut config: CoreInstanceRuntimeConfig,
+        merge: impl FnOnce(&CoreInstanceRuntimeConfig, &mut CoreInstanceRuntimeConfig),
+    ) -> Arc<CoreInstanceRuntimeConfig> {
+        let _update = self.inner.update.lock();
+        let current = self.inner.snapshot.load_full();
+        merge(&current, &mut config);
+        let config = Arc::new(config);
+        self.inner.snapshot.store(config.clone());
+        self.inner.peer_changes.send_modify(|version| *version += 1);
+        self.inner
+            .service_changes
+            .send_modify(|version| *version += 1);
+        config
+    }
+
     pub fn update_services(&self, update: impl FnOnce(&mut CoreRuntimeConfig)) {
         let _update = self.inner.update.lock();
         let mut config = self.inner.snapshot.load_full().as_ref().clone();

easytier-core/src/config/toml.rs

@@ -624,7 +624,7 @@ impl TomlConfig {
     }
 }
 
-#[cfg(feature = "management")]
+#[cfg(feature = "web-client")]
 mod snapshot;
 
 impl ConfigLoader for TomlConfig {