Fix #7575: Correct interface check for filer address function in admin server (#7588)

* Fix #7575: Correct interface check for filer address function in admin server

Problem:
User creation in object store was failing with error:
'filer_etc: filer address function not configured'

Root Cause:
In admin_server.go, the code checked for incorrect interface method
SetFilerClient(string, grpc.DialOption) instead of the actual
SetFilerAddressFunc(func() pb.ServerAddress, grpc.DialOption)

This interface mismatch prevented the filer address function from being
configured, causing user creation operations to fail.

Solution:
- Fixed interface check to use SetFilerAddressFunc
- Updated function call to properly configure filer address function
- Function now dynamically returns current active filer address

Tests Added:
- Unit tests in weed/admin/dash/user_management_test.go
- Integration tests in test/admin/user_creation_integration_test.go
- Documentation in test/admin/README.md

All tests pass successfully.

* Fix #7575: Correct interface check for filer address function in admin UI

Problem:
User creation in Admin UI was failing with error:
'filer_etc: filer address function not configured'

Root Cause:
In admin_server.go, the code checked for incorrect interface method
SetFilerClient(string, grpc.DialOption) instead of the actual
SetFilerAddressFunc(func() pb.ServerAddress, grpc.DialOption)

This interface mismatch prevented the filer address function from being
configured, causing user creation operations to fail in the Admin UI.

Note: This bug only affects the Admin UI. The S3 API and weed shell
commands (s3.configure) were unaffected as they use the correct interface
or bypass the credential manager entirely.

Solution:
- Fixed interface check in admin_server.go to use SetFilerAddressFunc
- Updated function call to properly configure filer address function
- Function now dynamically returns current active filer (HA-aware)
- Cleaned up redundant comments in the code

Tests Added:
- Unit tests in weed/admin/dash/user_management_test.go
  * TestFilerAddressFunctionInterface - verifies correct interface
  * TestGenerateAccessKey - tests key generation
  * TestGenerateSecretKey - tests secret generation
  * TestGenerateAccountId - tests account ID generation

All tests pass and will run automatically in CI.

* Fix #7575: Correct interface check for filer address function in admin UI

Problem:
User creation in Admin UI was failing with error:
'filer_etc: filer address function not configured'

Root Cause:
1. In admin_server.go, the code checked for incorrect interface method
   SetFilerClient(string, grpc.DialOption) instead of the actual
   SetFilerAddressFunc(func() pb.ServerAddress, grpc.DialOption)
2. The admin command was missing the filer_etc import, so the store
   was never registered

This interface mismatch prevented the filer address function from being
configured, causing user creation operations to fail in the Admin UI.

Note: This bug only affects the Admin UI. The S3 API and weed shell
commands (s3.configure) were unaffected as they use the correct interface
or bypass the credential manager entirely.

Solution:
- Added filer_etc import to weed/command/admin.go to register the store
- Fixed interface check in admin_server.go to use SetFilerAddressFunc
- Updated function call to properly configure filer address function
- Function now dynamically returns current active filer (HA-aware)
- Hoisted credentialManager assignment to reduce code duplication

Tests Added:
- Unit tests in weed/admin/dash/user_management_test.go
  * TestFilerAddressFunctionInterface - verifies correct interface
  * TestGenerateAccessKey - tests key generation
  * TestGenerateSecretKey - tests secret generation
  * TestGenerateAccountId - tests account ID generation

All tests pass and will run automatically in CI.

weed/command/admin.go

@@ -22,6 +22,7 @@ import (
 	"github.com/seaweedfs/seaweedfs/weed/admin"
 	"github.com/seaweedfs/seaweedfs/weed/admin/dash"
 	"github.com/seaweedfs/seaweedfs/weed/admin/handlers"
+	_ "github.com/seaweedfs/seaweedfs/weed/credential/filer_etc" // Register filer_etc credential store
 	"github.com/seaweedfs/seaweedfs/weed/pb"
 	"github.com/seaweedfs/seaweedfs/weed/security"
 	"github.com/seaweedfs/seaweedfs/weed/util"