refactor: major codebase improvements and test framework overhaul

This commit represents a comprehensive refactoring of the codebase focused on
improving code quality, testability, and maintainability.

Key improvements:
- Implement dependency injection and interface-based architecture
- Add comprehensive test framework with fixtures and test suites
- Fix all linting issues (errcheck, gosec, staticcheck, goconst, etc.)
- Achieve full EditorConfig compliance across all files
- Replace hardcoded test data with proper fixture files
- Add configuration loader with hierarchical config support
- Improve error handling with contextual information
- Add progress indicators for better user feedback
- Enhance Makefile with help system and improved editorconfig commands
- Consolidate constants and remove deprecated code
- Strengthen validation logic for GitHub Actions
- Add focused consumer interfaces for better separation of concerns

Testing improvements:
- Add comprehensive integration tests
- Implement test executor pattern for better test organization
- Create extensive YAML fixture library for testing
- Fix all failing tests and improve test coverage
- Add validation test fixtures to avoid embedded YAML in Go files

Build and tooling:
- Update Makefile to show help by default
- Fix editorconfig commands to use eclint properly
- Add comprehensive help documentation to all make targets
- Improve file selection patterns to avoid glob errors

This refactoring maintains backward compatibility while significantly
improving the internal architecture and developer experience.

internal/validation/validation.go

@@ -25,16 +25,19 @@ func IsSemanticVersion(version string) bool {
 
 // IsVersionPinned checks if a semantic version is pinned to a specific version.
 func IsVersionPinned(version string) bool {
-	// Consider it pinned if it specifies patch version (v1.2.3) or is a commit SHA
-	if IsSemanticVersion(version) {
-		return true
-	}
-	return IsCommitSHA(version) && len(version) == 40 // Only full SHAs are considered pinned
+	// Consider it pinned if it specifies patch version (v1.2.3) or is a full commit SHA
+	return IsSemanticVersion(version) || (IsCommitSHA(version) && len(version) == 40)
 }
 
 // ValidateGitBranch checks if a branch exists in the given repository.
 func ValidateGitBranch(repoRoot, branch string) bool {
-	cmd := exec.Command("git", "show-ref", "--verify", "--quiet", "refs/heads/"+branch)
+	cmd := exec.Command(
+		"git",
+		"show-ref",
+		"--verify",
+		"--quiet",
+		"refs/heads/"+branch,
+	) // #nosec G204 -- branch name validated by git
 	cmd.Dir = repoRoot
 	return cmd.Run() == nil
 }