chore: remove ~50k lines of unreachable dead code (#8913)

* chore: remove unreachable dead code across the codebase

Remove ~50,000 lines of unreachable code identified by static analysis.

Major removals:
- weed/filer/redis_lua: entire unused Redis Lua filer store implementation
- weed/wdclient/net2, resource_pool: unused connection/resource pool packages
- weed/plugin/worker/lifecycle: unused lifecycle plugin worker
- weed/s3api: unused S3 policy templates, presigned URL IAM, streaming copy,
  multipart IAM, key rotation, and various SSE helper functions
- weed/mq/kafka: unused partition mapping, compression, schema, and protocol functions
- weed/mq/offset: unused SQL storage and migration code
- weed/worker: unused registry, task, and monitoring functions
- weed/query: unused SQL engine, parquet scanner, and type functions
- weed/shell: unused EC proportional rebalance functions
- weed/storage/erasure_coding/distribution: unused distribution analysis functions
- Individual unreachable functions removed from 150+ files across admin,
  credential, filer, iam, kms, mount, mq, operation, pb, s3api, server,
  shell, storage, topology, and util packages

* fix(s3): reset shared memory store in IAM test to prevent flaky failure

TestLoadIAMManagerFromConfig_EmptyConfigWithFallbackKey was flaky because
the MemoryStore credential backend is a singleton registered via init().
Earlier tests that create anonymous identities pollute the shared store,
causing LookupAnonymous() to unexpectedly return true.

Fix by calling Reset() on the memory store before the test runs.

* style: run gofmt on changed files

* fix: restore KMS functions used by integration tests

* fix(plugin): prevent panic on send to closed worker session channel

The Plugin.sendToWorker method could panic with "send on closed channel"
when a worker disconnected while a message was being sent. The race was
between streamSession.close() closing the outgoing channel and sendToWorker
writing to it concurrently.

Add a done channel to streamSession that is closed before the outgoing
channel, and check it in sendToWorker's select to safely detect closed
sessions without panicking.

weed/s3api/object_lock_utils.go

@@ -2,8 +2,6 @@ package s3api
 
 import (
 	"context"
-	"encoding/xml"
-	"fmt"
 	"strconv"
 	"time"
 
@@ -35,21 +33,6 @@ func StoreVersioningInExtended(entry *filer_pb.Entry, enabled bool) error {
 	return nil
 }
 
-// LoadVersioningFromExtended loads versioning configuration from entry extended attributes
-func LoadVersioningFromExtended(entry *filer_pb.Entry) (bool, bool) {
-	if entry == nil || entry.Extended == nil {
-		return false, false // not found, default to suspended
-	}
-
-	// Check for S3 API compatible key
-	if versioningBytes, exists := entry.Extended[s3_constants.ExtVersioningKey]; exists {
-		enabled := string(versioningBytes) == s3_constants.VersioningEnabled
-		return enabled, true
-	}
-
-	return false, false // not found
-}
-
 // GetVersioningStatus returns the versioning status as a string: "", "Enabled", or "Suspended"
 // Empty string means versioning was never enabled
 func GetVersioningStatus(entry *filer_pb.Entry) string {
@@ -90,15 +73,6 @@ func CreateObjectLockConfiguration(enabled bool, mode string, days int, years in
 	return config
 }
 
-// ObjectLockConfigurationToXML converts ObjectLockConfiguration to XML bytes
-func ObjectLockConfigurationToXML(config *ObjectLockConfiguration) ([]byte, error) {
-	if config == nil {
-		return nil, fmt.Errorf("object lock configuration is nil")
-	}
-
-	return xml.Marshal(config)
-}
-
 // StoreObjectLockConfigurationInExtended stores Object Lock configuration in entry extended attributes
 func StoreObjectLockConfigurationInExtended(entry *filer_pb.Entry, config *ObjectLockConfiguration) error {
 	if entry.Extended == nil {
@@ -379,18 +353,6 @@ func validateDefaultRetention(retention *DefaultRetention) error {
 	return nil
 }
 
-// ====================================================================
-// SHARED OBJECT LOCK CHECKING FUNCTIONS
-// ====================================================================
-// These functions delegate to s3_objectlock package to avoid code duplication.
-// They are kept here for backward compatibility with existing callers.
-
-// EntryHasActiveLock checks if an entry has an active retention or legal hold
-// Delegates to s3_objectlock.EntryHasActiveLock
-func EntryHasActiveLock(entry *filer_pb.Entry, currentTime time.Time) bool {
-	return s3_objectlock.EntryHasActiveLock(entry, currentTime)
-}
-
 // HasObjectsWithActiveLocks checks if any objects in the bucket have active retention or legal hold
 // Delegates to s3_objectlock.HasObjectsWithActiveLocks
 func HasObjectsWithActiveLocks(ctx context.Context, client filer_pb.SeaweedFilerClient, bucketPath string) (bool, error) {