Build the scanner that reads bundles and fields into a ModelMap

Problem/Motivation

Everything downstream — the planner, the generator, the change queue, the conventions — reads one thing: a normalized description of what the site's content model contains. It has to come from the live site, because none of the three sites keeps an exported configuration; the model exists only in the database.

Proposed resolution

• A Scanner service that walks every content entity type, its bundles and its field definitions, and returns an immutable ModelMap value object.
• Per field, record what a decision actually needs: machine name, type, cardinality, required flag, target type and target bundles for references, settings that change the output shape (image style, text format, date type), and whether it is a base field or a configured one.
• Record nothing that is not needed for a decision — the map is read by humans in review, and a dump of the field storage is not.
• Make the map serializable and comparable, so two scans can be diffed; the change queue is built on that comparison.

Remaining tasks

Everything.