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/services/ollama-cloud.ts

@@ -405,7 +405,7 @@ AUDIENCE STYLE: ${audienceStyle}
 ${organization ? `ORGANIZATION BRANDING: ${organization}` : ""}
 
 REQUIREMENTS:
-- Create EXACTLY ${slideCount} slides
+- ${slideCount > 0 ? `Create EXACTLY ${slideCount} slides` : "Maintain the exact number of slides/pages from the provided source presentation/document context. If no source file is provided, generate 10 slides by default."}
 - ALL content in ${language}
 - Each slide MUST have complete htmlContent with inline <style> tags
 - Use animation-delay for staggered reveal effects