Schema: models + GET/PUT /api/lists/{id}/schema service #17

Scope

Model the DSL and add both schema calls to Services/InterlinedApiClient.Lists.cs.

Models (InterlinedList/Models/)

• ListSchema — Name (required), Description, Fields (>= 1).
• ListField — Key, Type, Label (required) + Required, DefaultValue, Options, Placeholder, HelpText, Validation, Visible, Visibility, DisplayOrder.
• ListFieldValidation — Min, Max, MinLength, MaxLength, Pattern, Step.
• ListFieldVisibility — Condition { Field, Operator, Value }.
• ListFieldType — the twelve types as a constrained set: text, textarea, number, boolean, date, datetime, email, url, tel, select, multiselect, priority.

Note the wire mapping: each fields[] entry is stored as a ListProperty (key→propertyKey, label→propertyName, type→propertyType) — the properties body shape uses those names.

Service

• GetListSchemaAsync(listId) → GET, response is wrapped: {"data": {...}}.
• PutListSchemaDslAsync(listId, ListSchema) → destructive rebuild.
• PutListPropertiesAsync(listId, properties) → non-destructive edits.
• CreateListAsync gains an optional schema argument.

Error handling

400 responses name the offending column, e.g.
Invalid schema: Field 'year' has invalid type 'integer'. Valid types: text, number, ...
Surface that message against the field, not as a generic failure. Also handle: missing name, empty fields, a field missing key/type/label, select/multiselect without options, duplicate keys.

Acceptance criteria

• All four service methods land, shapes verified live against the test account.
• ListSummary keeps compiling; schema is fetched separately, not folded into it.
• A round-trip test (read schema → PUT it back unchanged) is verified on a throwaway test list.