* client/proxy: extract wrapWorkConn to deduplicate UDP/SUDP connection wrapping
Move the repeated rate-limiting, encryption, and compression wrapping
logic from UDPProxy and SUDPProxy into a shared BaseProxy.wrapWorkConn
method, reducing ~18 lines of duplication in each proxy type.
* client/proxy: unify work conn wrapping with pooled compression for all proxy types
Refactor wrapWorkConn to accept encKey parameter and return
(io.ReadWriteCloser, recycleFn, error), enabling HandleTCPWorkConnection
to reuse the same limiter/encryption/compression pipeline.
Switch all proxy types from WithCompression to WithCompressionFromPool.
TCP non-plugin path calls recycleFn via defer after Join; plugin and
UDP/SUDP paths skip recycle (objects are GC'd safely, per golib contract).
Fix connection leaks in multiple error paths across client and server:
- server/proxy/http: close tmpConn when WithEncryption fails
- client/proxy: close localConn when ProxyProtocol WriteTo fails
- client/visitor/sudp: close visitorConn on all error paths in getNewVisitorConn
- client/visitor/xtcp: close tunnelConn when WithEncryption fails
- client/visitor/xtcp: close lConn when NewKCPConnFromUDP fails
- pkg/plugin/client/unix_domain_socket: close localConn and connInfo.Conn when WriteTo fails, close connInfo.Conn when DialUnix fails
- pkg/plugin/client/tls2raw: close tlsConn when Handshake or Dial fails
* support bandwidth_limit set by server plugin
* limiter at proxy level
* bandwidth_limit_mode
* updates tests for bandwidth_limit_mode default
* bandwidth_limit_mode as string
* add checkForSrv for bandwidth_limit_mode
* bandwidth_limit flags for sub cmds
* gci write
