fix(registry): reintroduce option to skip tls verification (#312)

- Add WATCHTOWER_REGISTRY_TLS_SKIP and WATCHTOWER_REGISTRY_TLS_MIN_VERSION flags in flags.go
- Refactor auth.go with Client interface for improved testability
- Update manifest.go to support HTTP URLs with TLS skip
- Enhance digest.go to error on empty tokens
- Add tests for HTTP registries and malformed headers in auth_test.go, digest_test.go
- Update .mockery.yaml to v3.3.2 and generate AuthClient.go
- Reorganize and improve documentation navigation and arguments page

Closes #309

Author: nicholas-fedor

.mockery.yaml

@@ -5,15 +5,15 @@
 # Watchtower: https://github.com/nicholas-fedor/watchtower/                                          #
 # Mockery: https://vektra.github.io/mockery/latest/                                                  #
 # Configuration: https://vektra.github.io/mockery/latest/configuration                               #
-# Mockery Version: 2.53                                                                              #
+# Mockery Version: 3.3.2                                                                              #
 #                                                                                                    #
 ######################################################################################################
 
 ######################################################################################################
 # Mockery Usage                                                                                      #
 #                                                                                                    #
 # Install Mockery:                                                                                   #
-# go install github.com/vektra/mockery/[email protected]                                                     #
+# go install github.com/vektra/mockery/[email protected]                                                     #
 #                                                                                                    #
 # Run CLI command from root:                                                                         #
 # mockery                                                                                            #
@@ -65,7 +65,7 @@
 # Disable all warnings for deprecated behavior.
 # When true, suppresses deprecation messages (e.g., for quiet, with-expecter in v3).
 # Default: false
-disable-deprecation-warnings: true
+# disable-deprecation-warnings: true
 
 # Selectively disable specific deprecation warnings by name.
 # Use names from deprecation-name in log messages (e.g., "quiet", "with-expecter").
@@ -142,7 +142,7 @@ recursive: true
 # Generate testify expecter methods (e.g., EXPECT()) for mocks when true.
 # Enhances compatibility with github.com/stretchr/testify; v3 deprecation: permanently enabled.
 # Default: false
-with-expecter: true
+# with-expecter: true
 
 # Specify build tags for the generated mock files.
 # Matches Go’s build constraint syntax (e.g., "// +build tag1,tag2").
@@ -157,7 +157,7 @@ with-expecter: true
 
 # Package name for generated mock files.
 # Default: "{{.PackageName}}"
-outpkg: mocks
+pkgname: "mocks"
 
 # Treat variadic parameters as a single slice when false, rather than unrolling them.
 # Affects how variadic methods are mocked (e.g., func(...int) vs. func([]int)).