chore: adopt remote dprint config, tidy examples

Extend dprint from a shared remote config and add the prettier
and exec plugins, formatting TOML via a new tombi.toml instead
of golangci-lint fmt. Taskfile.yml, scripts/build.sh, and
html_styles.css pick up the resulting reformat.

Exporter examples now write to a temp dir and clean up after
themselves instead of leaving output.md/.docx/.html in the
repo. Drop the stray internal/exporters/output.docx and ignore
internal/exporters/output.* going forward.

internal/exporters/example_test.go

@@ -4,12 +4,25 @@ package exporters_test
 import (
 	"fmt"
 	"log"
+	"os"
+	"path/filepath"
 
 	"github.com/kjanat/articulate-parser/internal/exporters"
 	"github.com/kjanat/articulate-parser/internal/models"
 	"github.com/kjanat/articulate-parser/internal/services"
 )
 
+// tempOutput returns a path inside a fresh temp dir plus a cleanup func, so
+// example exports don't pollute the package source tree. Example functions
+// can't take *testing.T, so t.TempDir is unavailable here.
+func tempOutput(name string) (path string, cleanup func()) {
+	dir, err := os.MkdirTemp("", "exporters-example-*")
+	if err != nil {
+		log.Fatal(err)
+	}
+	return filepath.Join(dir, name), func() { _ = os.RemoveAll(dir) }
+}
+
 // ExampleNewFactory demonstrates creating an exporter factory.
 func ExampleNewFactory() {
 	htmlCleaner := services.NewHTMLCleaner()
@@ -69,7 +82,9 @@ func ExampleMarkdownExporter_Export() {
 	}
 
 	// Export to markdown file
-	err := exporter.Export(course, "output.md")
+	out, cleanup := tempOutput("output.md")
+	defer cleanup()
+	err := exporter.Export(course, out)
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -91,7 +106,9 @@ func ExampleDocxExporter_Export() {
 	}
 
 	// Export to Word document
-	err := exporter.Export(course, "output.docx")
+	out, cleanup := tempOutput("output.docx")
+	defer cleanup()
+	err := exporter.Export(course, out)
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -121,7 +138,9 @@ func ExampleHTMLExporter_Export() {
 	}
 
 	// Export to HTML file
-	err := exporter.Export(course, "output.html")
+	out, cleanup := tempOutput("output.html")
+	defer cleanup()
+	err := exporter.Export(course, out)
 	if err != nil {
 		log.Fatal(err)
 	}

internal/exporters/html_styles.css

@@ -1,7 +1,13 @@
 body {
 	font-family:
-		-apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu,
-		Cantarell, sans-serif;
+		-apple-system,
+		BlinkMacSystemFont,
+		"Segoe UI",
+		Roboto,
+		Oxygen,
+		Ubuntu,
+		Cantarell,
+		sans-serif;
 	line-height: 1.6;
 	color: #333;
 	max-width: 800px;