fix: comprehensive go vet error fixes and add CI enforcement (#7861)

* fix: use keyed fields in struct literals

- Replace unsafe reflect.StringHeader/SliceHeader with safe unsafe.String/Slice (weed/query/sqltypes/unsafe.go)
- Add field names to Type_ScalarType struct literals (weed/mq/schema/schema_builder.go)
- Add Duration field name to FlexibleDuration struct literals across test files
- Add field names to bson.D struct literals (weed/filer/mongodb/mongodb_store_kv.go)

Fixes go vet warnings about unkeyed struct literals.

* fix: remove unreachable code

- Remove unreachable return statements after infinite for loops
- Remove unreachable code after if/else blocks where all paths return
- Simplify recursive logic by removing unnecessary for loop (inode_to_path.go)
- Fix Type_ScalarType literal to use enum value directly (schema_builder.go)
- Call onCompletionFn on stream error (subscribe_session.go)

Files fixed:
- weed/query/sqltypes/unsafe.go
- weed/mq/schema/schema_builder.go
- weed/mq/client/sub_client/connect_to_sub_coordinator.go
- weed/filer/redis3/ItemList.go
- weed/mq/client/agent_client/subscribe_session.go
- weed/mq/broker/broker_grpc_pub_balancer.go
- weed/mount/inode_to_path.go
- weed/util/skiplist/name_list.go

* fix: avoid copying lock values in protobuf messages

- Use proto.Merge() instead of direct assignment to avoid copying sync.Mutex in S3ApiConfiguration (iamapi_server.go)
- Add explicit comments noting that channel-received values are already copies before taking addresses (volume_grpc_client_to_master.go)

The protobuf messages contain sync.Mutex fields from the message state, which should not be copied.
Using proto.Merge() properly merges messages without copying the embedded mutex.

* fix: correct byte array size for uint32 bit shift operations

The generateAccountId() function only needs 4 bytes to create a uint32 value.
Changed from allocating 8 bytes to 4 bytes to match the actual usage.

This fixes go vet warning about shifting 8-bit values (bytes) by more than 8 bits.

* fix: ensure context cancellation on all error paths

In broker_client_subscribe.go, ensure subscriberCancel() is called on all error return paths:
- When stream creation fails
- When partition assignment fails
- When sending initialization message fails

This prevents context leaks when an error occurs during subscriber creation.

* fix: ensure subscriberCancel called for CreateFreshSubscriber stream.Send error

Ensure subscriberCancel() is called when stream.Send fails in CreateFreshSubscriber.

* ci: add go vet step to prevent future lint regressions

- Add go vet step to GitHub Actions workflow
- Filter known protobuf lock warnings (MessageState sync.Mutex)
  These are expected in generated protobuf code and are safe
- Prevents accumulation of go vet errors in future PRs
- Step runs before build to catch issues early

* fix: resolve remaining syntax and logic errors in vet fixes

- Fixed syntax errors in filer_sync.go caused by missing closing braces
- Added missing closing brace for if block and function
- Synchronized fixes to match previous commits on branch

* fix: add missing return statements to daemon functions

- Add 'return false' after infinite loops in filer_backup.go and filer_meta_backup.go
- Satisfies declared bool return type signatures
- Maintains consistency with other daemon functions (runMaster, runFilerSynchronize, runWorker)
- While unreachable, explicitly declares the return satisfies function signature contract

* fix: add nil check for onCompletionFn in SubscribeMessageRecord

- Check if onCompletionFn is not nil before calling it
- Prevents potential panic if nil function is passed
- Matches pattern used in other callback functions

* docs: clarify unreachable return statements in daemon functions

- Add comments documenting that return statements satisfy function signature
- Explains that these returns follow infinite loops and are unreachable
- Improves code clarity for future maintainers

weed/iamapi/iamapi_server.go

@@ -23,6 +23,7 @@ import (
 	"github.com/seaweedfs/seaweedfs/weed/util"
 	"github.com/seaweedfs/seaweedfs/weed/wdclient"
 	"google.golang.org/grpc"
+	"google.golang.org/protobuf/proto"
 )
 
 type IamS3ApiConfig interface {
@@ -46,11 +47,11 @@ type IamServerOption struct {
 }
 
 type IamApiServer struct {
-	s3ApiConfig      IamS3ApiConfig
-	iam              *s3api.IdentityAccessManagement
-	shutdownContext  context.Context
-	shutdownCancel   context.CancelFunc
-	masterClient     *wdclient.MasterClient
+	s3ApiConfig     IamS3ApiConfig
+	iam             *s3api.IdentityAccessManagement
+	shutdownContext context.Context
+	shutdownCancel  context.CancelFunc
+	masterClient    *wdclient.MasterClient
 }
 
 var s3ApiConfigure IamS3ApiConfig
@@ -63,19 +64,19 @@ func NewIamApiServerWithStore(router *mux.Router, option *IamServerOption, expli
 	if len(option.Filers) == 0 {
 		return nil, fmt.Errorf("at least one filer address is required")
 	}
-	
+
 	masterClient := wdclient.NewMasterClient(option.GrpcDialOption, "", "iam", "", "", "", *pb.NewServiceDiscoveryFromMap(option.Masters))
-	
+
 	// Create a cancellable context for the master client connection
 	// This allows graceful shutdown via Shutdown() method
 	shutdownCtx, shutdownCancel := context.WithCancel(context.Background())
-	
+
 	// Start KeepConnectedToMaster for volume location lookups
 	// IAM config files are typically small and inline, but if they ever have chunks,
 	// ReadEntry→StreamContent needs masterClient for volume lookups
 	glog.V(0).Infof("IAM API starting master client connection for volume location lookups")
 	go masterClient.KeepConnectedToMaster(shutdownCtx)
-	
+
 	configure := &IamS3ApiConfigure{
 		option:       option,
 		masterClient: masterClient,
@@ -143,7 +144,8 @@ func (iama *IamS3ApiConfigure) GetS3ApiConfigurationFromCredentialManager(s3cfg
 	if err != nil {
 		return fmt.Errorf("failed to load configuration from credential manager: %w", err)
 	}
-	*s3cfg = *config
+	// Use proto.Merge to avoid copying the sync.Mutex embedded in the message
+	proto.Merge(s3cfg, config)
 	return nil
 }