v3.1.5

🐛 Bug Fix: Better Fake Image Detection

Problem: Some models hallucinate image generation by describing an image in text without calling the generate_image tool. The previous fix only detected placeholder URLs.

Fix:

• Now also detects when the user asked for an image but no tool was called
• Checks for image-related keywords in the user's message (English + Portuguese)
• Strengthened system prompt to explicitly forbid placeholder URLs
• Clearer error message explaining the correct flow:
  1. Selected model should call generate_image tool with a detailed prompt
  2. Tool internally calls the image model (Flux.1-Dev, etc.)
  3. Generated image is returned and displayed

Changes:

• ViewModels/ChatViewModel.swift — Detect user image requests + missing tool calls
• Models/SystemPrompt.swift — Stronger anti-hallucination instructions
• Bump version to 3.1.5