Scheduled Facebook Insights Sync to Google Sheets

# 03a. Caption Generation

**Purpose:** Uses Google Gemini to write a short, engaging social media caption **specifically tailored for the target platform**. The caption complements the image (represented by the first generated prompt) and aligns with the overall content strategy. Includes relevant hashtags.

**Input (from Nodes '1. Get Next Post Idea', '3a. Generate Content Concept', '3b. Generate Image Prompt Options'):**
*   `ImagePrompt` (string: The *first* prompt from step 3b)
*   `ChosenIdea` (string: Concept from step 3a)
*   `OriginalTopic` (string)
*   `TargetAudience` (string)
*   `BrandVoice` (string)
*   `Platform` (string: 'Instagram' or 'LinkedIn')

**Output (JSON):**
*   `{"Caption": "Generated caption text with #hashtags..."}`