refactor: comprehensive code quality improvements

- Add logger to all exporters for consistent error handling
- Add Course.Validate() method with ValidationError type
- Create shared test fixtures in internal/testdata
- Refactor config passing: NewArticulateParser now takes *config.Config
- Add NewLoggerFromConfig() factory for logger creation
- Add context cancellation with signal handling (SIGINT/SIGTERM)
- Add godoc examples for loggers and exporters
- Add HTML exporter error path tests
- Add fuzz tests for parser and HTMLCleaner
- Fix markdown output: trim whitespace, collapse blank lines
- Remove test output files from repo

internal/exporters/bench_test.go

@@ -6,12 +6,13 @@ import (
 
 	"github.com/kjanat/articulate-parser/internal/models"
 	"github.com/kjanat/articulate-parser/internal/services"
+	"github.com/kjanat/articulate-parser/internal/testdata"
 )
 
 // BenchmarkFactory_CreateExporter_Markdown benchmarks markdown exporter creation.
 func BenchmarkFactory_CreateExporter_Markdown(b *testing.B) {
 	htmlCleaner := services.NewHTMLCleaner()
-	factory := NewFactory(htmlCleaner)
+	factory := NewFactory(htmlCleaner, nil)
 
 	b.ResetTimer()
 	for b.Loop() {
@@ -22,7 +23,7 @@ func BenchmarkFactory_CreateExporter_Markdown(b *testing.B) {
 // BenchmarkFactory_CreateExporter_All benchmarks creating all exporter types.
 func BenchmarkFactory_CreateExporter_All(b *testing.B) {
 	htmlCleaner := services.NewHTMLCleaner()
-	factory := NewFactory(htmlCleaner)
+	factory := NewFactory(htmlCleaner, nil)
 	formats := []string{"markdown", "docx", "html"}
 
 	b.ResetTimer()
@@ -36,15 +37,15 @@ func BenchmarkFactory_CreateExporter_All(b *testing.B) {
 // BenchmarkAllExporters_Export benchmarks all exporters with the same course.
 func BenchmarkAllExporters_Export(b *testing.B) {
 	htmlCleaner := services.NewHTMLCleaner()
-	course := createBenchmarkCourse()
+	course := testdata.BasicCourse()
 
 	exporters := map[string]struct {
 		exporter any
 		ext      string
 	}{
-		"Markdown": {NewMarkdownExporter(htmlCleaner), ".md"},
-		"Docx":     {NewDocxExporter(htmlCleaner), ".docx"},
-		"HTML":     {NewHTMLExporter(htmlCleaner), ".html"},
+		"Markdown": {NewMarkdownExporter(htmlCleaner, nil), ".md"},
+		"Docx":     {NewDocxExporter(htmlCleaner, nil), ".docx"},
+		"HTML":     {NewHTMLExporter(htmlCleaner, nil), ".html"},
 	}
 
 	for name, exp := range exporters {
@@ -66,10 +67,10 @@ func BenchmarkAllExporters_Export(b *testing.B) {
 // BenchmarkExporters_LargeCourse benchmarks exporters with large course data.
 func BenchmarkExporters_LargeCourse(b *testing.B) {
 	htmlCleaner := services.NewHTMLCleaner()
-	course := createLargeBenchmarkCourse()
+	course := testdata.LargeCourse(50)
 
 	b.Run("Markdown_Large", func(b *testing.B) {
-		exporter := NewMarkdownExporter(htmlCleaner)
+		exporter := NewMarkdownExporter(htmlCleaner, nil)
 		tempDir := b.TempDir()
 
 		b.ResetTimer()
@@ -80,7 +81,7 @@ func BenchmarkExporters_LargeCourse(b *testing.B) {
 	})
 
 	b.Run("Docx_Large", func(b *testing.B) {
-		exporter := NewDocxExporter(htmlCleaner)
+		exporter := NewDocxExporter(htmlCleaner, nil)
 		tempDir := b.TempDir()
 
 		b.ResetTimer()
@@ -91,7 +92,7 @@ func BenchmarkExporters_LargeCourse(b *testing.B) {
 	})
 
 	b.Run("HTML_Large", func(b *testing.B) {
-		exporter := NewHTMLExporter(htmlCleaner)
+		exporter := NewHTMLExporter(htmlCleaner, nil)
 		tempDir := b.TempDir()
 
 		b.ResetTimer()
@@ -101,100 +102,3 @@ func BenchmarkExporters_LargeCourse(b *testing.B) {
 		}
 	})
 }
-
-// createBenchmarkCourse creates a standard-sized course for benchmarking.
-func createBenchmarkCourse() *models.Course {
-	return &models.Course{
-		ShareID: "benchmark-id",
-		Author:  "Benchmark Author",
-		Course: models.CourseInfo{
-			ID:             "bench-course",
-			Title:          "Benchmark Course",
-			Description:    "Performance testing course",
-			NavigationMode: "menu",
-			Lessons: []models.Lesson{
-				{
-					ID:    "lesson1",
-					Title: "Introduction",
-					Type:  "lesson",
-					Items: []models.Item{
-						{
-							Type: "text",
-							Items: []models.SubItem{
-								{
-									Heading:   "Welcome",
-									Paragraph: "<p>This is a test paragraph with <strong>HTML</strong> content.</p>",
-								},
-							},
-						},
-						{
-							Type: "list",
-							Items: []models.SubItem{
-								{Paragraph: "Item 1"},
-								{Paragraph: "Item 2"},
-								{Paragraph: "Item 3"},
-							},
-						},
-					},
-				},
-			},
-		},
-	}
-}
-
-// createLargeBenchmarkCourse creates a large course for stress testing.
-func createLargeBenchmarkCourse() *models.Course {
-	lessons := make([]models.Lesson, 50)
-	for i := range 50 {
-		lessons[i] = models.Lesson{
-			ID:          string(rune(i)),
-			Title:       "Lesson " + string(rune(i)),
-			Type:        "lesson",
-			Description: "<p>This is lesson description with <em>formatting</em>.</p>",
-			Items: []models.Item{
-				{
-					Type: "text",
-					Items: []models.SubItem{
-						{
-							Heading:   "Section Heading",
-							Paragraph: "<p>Content with <strong>bold</strong> and <em>italic</em> text.</p>",
-						},
-					},
-				},
-				{
-					Type: "list",
-					Items: []models.SubItem{
-						{Paragraph: "Point 1"},
-						{Paragraph: "Point 2"},
-						{Paragraph: "Point 3"},
-					},
-				},
-				{
-					Type: "knowledgeCheck",
-					Items: []models.SubItem{
-						{
-							Title: "Quiz Question",
-							Answers: []models.Answer{
-								{Title: "Answer A", Correct: false},
-								{Title: "Answer B", Correct: true},
-								{Title: "Answer C", Correct: false},
-							},
-							Feedback: "Good job!",
-						},
-					},
-				},
-			},
-		}
-	}
-
-	return &models.Course{
-		ShareID: "large-benchmark-id",
-		Author:  "Benchmark Author",
-		Course: models.CourseInfo{
-			ID:          "large-bench-course",
-			Title:       "Large Benchmark Course",
-			Description: "Large performance testing course",
-			Lessons:     lessons,
-		},
-	}
-}