Add rich-text image description support to AI Automators
## Summary
Add optional rich-text image description support to AI Automators for AI-based formatted text fields, including metadata storage for generated image descriptions.
Related/source issue: https://git.drupalcode.org/project/ai_initiative/-/work_items/3585695
## Problem
AI Automators can use formatted text as input, but images embedded in that text are currently ignored unless they are already available through a separate image/media field.
This makes automations less accurate for content that depends on visual context (for example: summaries, quality checks, and editorial pre-screening prompts).
## Proposed solution
Add an advanced setting on AI-based formatted text automators:
- Include image descriptions in output (checkbox)
When enabled:
- Parse formatted text for embedded images
- Optionally include secure external image URLs
- Generate short image descriptions using a vision-capable model
- Append these descriptions to automator context
- Store structured metadata in a configurable field (JSON payload)
Suggested additional advanced settings:
- metadata target field
- include external images (default off)
- max images to process
- description prompt override
Expected behavior:
- Feature is opt-in (off by default)
- Existing automators remain unchanged unless enabled
- Metadata can be reused by downstream automations/workflows
## Affected modules / components
- ai_automators (primary)
- RuleBase / formatted text token generation
- automator advanced configuration UI
- helper/service for rich-text image extraction and metadata writing
issue