feat: add screenshot OCR extraction

internal/application/capture_ocr.go

@@ -0,0 +1,57 @@
+package application
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/mmmy/snapgo/internal/infrastructure/clipboard"
+)
+
+// OCRRecognizer describes a provider capable of extracting text from a PNG
+// screenshot.
+type OCRRecognizer interface {
+	RecognizeText(ctx context.Context, pngBytes []byte) (string, error)
+}
+
+// CaptureOCRService wires screenshot bytes -> OCR provider -> clipboard. It
+// leaves progress reporting to the caller so native and web overlays can share
+// the same status HUD.
+type CaptureOCRService struct {
+	Recognizer OCRRecognizer
+	Clipboard  clipboard.Writer
+}
+
+// Recognize asks the configured OCR provider to extract text from the PNG.
+func (s *CaptureOCRService) Recognize(ctx context.Context, pngBytes []byte) (string, error) {
+	if s.Recognizer == nil {
+		return "", fmt.Errorf("ocr is not configured")
+	}
+	if len(pngBytes) == 0 {
+		return "", fmt.Errorf("empty screenshot")
+	}
+	text, err := s.Recognizer.RecognizeText(ctx, pngBytes)
+	if err != nil {
+		return "", err
+	}
+	text = strings.TrimSpace(text)
+	if text == "" {
+		return "", fmt.Errorf("ocr result is empty")
+	}
+	return text, nil
+}
+
+// CopyText writes the extracted text to the clipboard.
+func (s *CaptureOCRService) CopyText(_ context.Context, text string) error {
+	text = strings.TrimSpace(text)
+	if text == "" {
+		return fmt.Errorf("empty ocr text")
+	}
+	if s.Clipboard == nil {
+		return fmt.Errorf("clipboard is not configured")
+	}
+	if err := s.Clipboard.WriteText(text); err != nil {
+		return fmt.Errorf("clipboard write failed: %w", err)
+	}
+	return nil
+}