Add a Drupal migrate analyst agent

[robertoperuzzo]

The Migration Analyst is an autonomous agent designed to support Drupal content migration projects. Its main goals are:

1. Source database analysis — connects to the source Drupal database, detects its version (D7 vs D8+), counts entity instances, and analyses field definitions and data population rates for any content bundle (nodes, paragraphs, taxonomy terms).
2. Structural investigation — identifies paragraph parent contexts, detects container/nested paragraph hierarchies, and distinguishes active instances from orphaned ones.
3. Field mapping proposals — scans the destination Drupal configuration and proposes source-to-destination field mappings when a target bundle is known.
4. Live example resolution — automatically resolves real page URLs for representative content examples, and optionally takes browser screenshots.
5. Structured reporting — produces a standardised analysis report with instance counts, field tables, population metrics, and live examples.
6. GitLab issue generation — formats a complete migration issue (in the specified language) from the analysis, ready to paste into GitLab, using a standardised template.
7. Technical breakdown — when asked, reads an existing GitLab issue and produces a developer-facing TO DO checklist for implementation planning.

The agent orchestrates atomic skills (database discovery, field queries, destination scanning, etc.) in the right order based on user intent, always confirming steps with the user before executing them.

[robertoperuzzo]

We can close this issue because I'm creating a claude plugin here https://github.com/sparkfabrik/sf-claude-plugins/pull/28