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/src/instance/virtual_nic.rs

@@ -663,7 +663,7 @@ impl VirtualNic {
 
         let dev = AsyncDevice::new(dev)?;
 
-        let flags = self.global_ctx.config.get_flags();
+        let flags = self.global_ctx.get_flags();
         let mut mtu_in_config = flags.mtu;
         if flags.enable_encryption {
             mtu_in_config -= 20;