feat(hostport): implement port-reuse with least-used allocation strategy (#327)

* feat: implement sharded lock for HostPort port allocation

- Add ShardCount config option for customizable shard count
- Replace global mutex with per-shard locks to reduce contention
- Use FNV-1a hash for consistent shard routing by GSS name
- Support parallel port allocation across different shards
- Default shard_count=1 for backward compatibility

* feat(hostport): optimize concurrent port allocation with lock-free design

- Replace sharded port pools with shared port pool
- Use sync.Map for lock-free port lookup
- Use atomic operations for port usage counting
- Sharded locks only for pod allocation records
- Change sharding key from GSS name to GS name for better distribution
- Increase MaxShardCount from 128 to 256

This optimization reduces lock contention from 100% to ~0.4% in
high-concurrency scenarios (500 workers).

* feat(hostport): implement port-reuse with least-used allocation strategy

- Replace portAmount/amountStat with portUsage counter array
- Implement least-used allocation for cross-node port reuse
- Remove unused shard_count config option
- Fix unused attrIntValue in nodeport_test.go (lint)

Author: chrisliu1995

.gitignore

@@ -25,6 +25,7 @@ testbin/*
 *.swo
 *~
 .vscode
+.qoder/
 
 # Temporary kustomize overlay for tracing
 config/.tracing-overlay-temp/
@@ -43,4 +44,7 @@ cover.out
 log_debug
 
 # Go cache
-.cache
+.cache
+
+# Local issue tracking
+问题/