Generate SEO content from trends spreadsheet to storage (SharePoint/Drive/Dropbox)

### Newsletter Template Branch  
**What it does**  
• Downloads your HTML template from SharePoint.  
• **Extract from Text File → Build Newsletter** replaces placeholders with AI-generated content.

**Credentials needed**  
Microsoft SharePoint OAuth2 (for **Get Newsletter Template**).

**User must provide**  
• Your own HTML template with these exact placeholders:  
  `{{INTRODUCTION_DE}} {{TOPIC_DE}} {{DESCRIPTION_DE}} {{TEASER1_DE}} {{TEASER2_DE}} {{TEASER3_DE}} {{CTA_DE}} {{FOOTER_TEXT_DE}} {{FOOTER_NAME_DE}} {{TOPIC_TITLE_EN}} {{INTRODUCTION_EN}} {{TOPIC_EN}} {{DESCRIPTION_EN}} {{TEASER1_EN}} {{TEASER2_EN}} {{TEASER3_EN}} {{CTA_EN}} {{FOOTER_TEXT_EN}} {{FOOTER_NAME_EN}}`  
• Upload this template to the SharePoint folder referenced in **Get Newsletter Template**.