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/Cargo.toml

@@ -413,14 +413,15 @@ extended-services = [
     "proxy-cidr-monitor",
 ]
 management = [
+    "web-client",
     "logging",
-    "management-rpc",
     "easytier-core/management",
     "easytier-proto/json-rpc",
     "easytier-proto/utils",
     "tokio/full",
 ]
 management-rpc = ["easytier-core/management-rpc"]
+web-client = ["management-rpc", "easytier-core/web-client"]
 tcp-hole-punch = ["easytier-core/tcp-hole-punch"]
 # Deprecated: hotpath profiling has been removed. These feature aliases are
 # retained as no-ops so existing build scripts using `--features hotpath*`