…ypes

Re-export FieldCondition, SubcategoryFieldDef, SubcategoryStructure from
funpayparsers.types.subcategory_structure via a new types module.

Add field_schema: list[SubcategoryFieldDef] field to OfferFields and a
subcategory_structure property that builds a SubcategoryStructure on demand.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

FieldCondition, SubcategoryFieldDef and SubcategoryStructure are now
proper Pydantic models inheriting from FunPayObject instead of
re-exporting the funpayparsers dataclasses directly.

Each class owns its _add_raw_source validator:
- FieldCondition/SubcategoryStructure: no raw_source on the parser side,
  generate a stable JSON identifier on construction
- SubcategoryFieldDef: raw_source already present on the parser dataclass,
  let from_attributes carry it through; fallback for dict construction

SubcategoryStructure.from_offer_fields is added as a classmethod and used
by OfferFields.subcategory_structure property. OfferFields.field_schema now
stores engine SubcategoryFieldDef instances.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Mirrors funpayparsers PR #102 (b942fae). The listing page parser
populates SubcategoryStructure from data-fields JSON; without this
field the structure was silently dropped on the engine side.

…e matching with parser

- label_map / lower_label_map now return dict[str, list[str]] and use
  cached_property, matching funpayparsers 66e6cd0. Previously a single-id
  dict silently dropped fields with duplicate labels (notably empty
  labels on form fields without <label>).
- FieldCondition.is_satisfied_by and stored values are case-insensitive
  via casefold, mirroring parser fc6190d. FunPay's listing page and
  offerEdit form render the same value with inconsistent casing.

Mirrors funpayparsers f2d2851. The parser stamps subcategory context
(OFFERS/CHIPS) onto every preview based on the offer URL; the engine
wrapper was dropping it.

…tegoryStructure validator

The parser ships SubcategoryStructure as a plain @DataClass (no
FunPayObject mixin). When pydantic ingests a parser instance via
model_validate, the existing 'before' validator only handled dict
input and returned dataclass instances unchanged, causing
'raw_source: Field required' validation errors on every page that
actually has a populated structure (e.g. subcat 1, 27, 41).

Mirrors the same pattern already used for FieldCondition. Verified on
live subcategories with rich filter blocks.

…fferPage.images

Mirrors funpayparsers (types/pages/order_page.py:53, types/pages/offer_page.py:48).
Both helpers were missing in engine, breaking the documented flow:

  message.meta.order_id -> get_order_page -> structure -> field_id mapping.

Also adds OfferPage.images (engine wrapper was missing the list parsed
from div.param-list attachments).

Verified end-to-end on live FunPay session.

…ields, OrderPage data split

Surfaces the new structural-parsing primitives from funpayparsers
feature/multi-source-label-index in the engine wrappers:

- SubcategoryFieldDef.aliases (casefolded set of cross-locale label aliases)
- SubcategoryStructure.label_map / lower_label_map now index aliases too,
  plus lookup_field_id(), add_alias(), enrich_from_offer() helpers
- OfferPreview.parse_title_fields(structure) and
  OrderPreview.parse_title_fields(structure) — delegate to parser's
  _parse_title_fields, extract NUMERIC_RANGE/SELECT/DROPDOWN suffix fields
  from comma-separated titles
- OrderPage.metadata (canonical-keyed stable order metadata) and
  lot_fields (everything else); get_structured_fields now operates on
  lot_fields, eliminating false matches against order metadata labels.
  Properties (short_description, amount, …) read from metadata directly.
- OrderPage.data kept for backwards compatibility.

Live recall on real subcategories:
- OfferPage.get_structured_fields: 0 → 3 matches after enrich_from_offer
- OrderPreview.parse_title_fields on subcat #1316 yields
  {currency: USD, usd: 20 USD} from a real purchase title.