feat: add content filter and code processing module (v0.3.0)

- Add content filter module (internal/content/)
- Implement basic character filtering (control chars, line breaks, symbols)
- Implement code block and inline code detection
- Implement comment detection for 30+ languages (JS/Python/Go/HTML/etc)
- Add go-enry dependency for intelligent language detection
- Add SkipKeywords config option (default: TODO/FIXME/HACK/XXX/etc)
- Integrate content processing into Translator
- Update config.yaml with skip_keywords

internal/content/content.go

@@ -0,0 +1,17 @@
+package content
+
+import (
+	"github.com/go-enry/go-enry/v2"
+)
+
+const (
+	Version = "1.0.0"
+)
+
+func DetectLanguage(text string) string {
+	return enry.GetLanguage("", []byte(text))
+}
+
+func Filter(text string) string {
+	return FilterBasic(text, nil)
+}