feat: remove espeak, add random voice/style selection, fix punctuation in TTS

- Removed espeak audio provider completely, now only uses OpenAI TTS
- Audio now uses random voice selection by default (can override with --openai-voice)
- Added --all-voices flag to generate audio in all 11 OpenAI voices
- Images now use random art styles (13 different styles including superhero, yoga, cat-themed)
- Fixed TTS to remove punctuation marks before speaking
- Updated Bulgarian pronunciation instructions to explicitly avoid Russian accent

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

1 files changed, 28 insertions, 0 deletions

diff --git a/internal/audio/validate.go b/internal/audio/validate.go
new file mode 100644
index 0000000..db042bd
--- /dev/null
+++ b/internal/audio/validate.go
@@ -0,0 +1,28 @@
+package audio
+
+import (
+	"fmt"
+	"strings"
+	"unicode"
+)
+
+// ValidateBulgarianText validates that the input text contains valid Bulgarian text
+func ValidateBulgarianText(text string) error {
+	if strings.TrimSpace(text) == "" {
+		return fmt.Errorf("text cannot be empty")
+	}
+	
+	hasCyrillic := false
+	for _, r := range text {
+		if unicode.In(r, unicode.Cyrillic) {
+			hasCyrillic = true
+			break
+		}
+	}
+	
+	if !hasCyrillic {
+		return fmt.Errorf("text must contain Cyrillic characters")
+	}
+	
+	return nil
+}
\ No newline at end of file