feat: add 'Same as source' option to slides count

- Added 'Same as source' to translations in EN, RU, HE
- Updated 'Number of Slides' dropdown to include 'Same as source' (value 0)
- Updated Qwen, Ollama, and Z.AI services to handle 0 slide count by instructing AI to match source structure

lib/i18n/translations.ts

@@ -121,6 +121,7 @@ export const translations = {
             audience: "Target Audience",
             animations: "Animation Style",
             numSlides: "Number of Slides",
+            sameAsSource: "Same as source",
             generate: "Generate Presentation",
             generating: "Crafting your story...",
             emptyState: "Your presentation will appear here",
@@ -281,6 +282,7 @@ export const translations = {
             audience: "Целевая аудитория",
             animations: "Стиль анимации",
             numSlides: "Количество слайдов",
+            sameAsSource: "Как в источнике",
             generate: "Создать презентацию",
             generating: "Создаем вашу историю...",
             emptyState: "Ваша презентация появится здесь",
@@ -441,6 +443,7 @@ export const translations = {
             audience: "קהל יעד",
             animations: "סגנון אנימציה",
             numSlides: "מספר שקופיות",
+            sameAsSource: "כמו במקור",
             generate: "חולל מצגת",
             generating: "יוצר את הסיפור שלך...",
             emptyState: "המצגת שלך תופיע כאן",