Story: Implement WKT decoding strategy #7

Goal

Introduce the WKT decoding foundation into spatial-decoder.

Implement a concrete WKT decoding strategy conforming to DecodeStrategyInterface and integrate it with the public Decoder API.

This Story must establish the parsing architecture and common mechanisms required to progressively support the WKT geometry types in subsequent Stories. The design must support the applicable coordinate dimensions and EMPTY representations without requiring later changes to the public decoding API.

Acceptance criteria

• A WKT decoding strategy implements DecodeStrategyInterface.
• The strategy is usable through the public Decoder API.
• The strategy accepts WKT text as input.
• The parsing architecture supports the progressive implementation of WKT geometry types.
• The architecture supports XY, XYZ, XYM and XYZM coordinate forms.
• The architecture supports EMPTY representations.
• Malformed or unsupported representations are explicitly rejected.
• Unsupported spatial information is never silently discarded or converted.
• The implementation has no runtime dependency on longitude-one/wkt-parser.
• Unit tests cover the strategy and its integration with Decoder.
• The standard test and quality suites pass.

Out of scope

• Implementation of all individual geometry types.
• Migration of legacy wkt-parser tests.
• EWKT.
• WKB or GeoJSON decoding.
• Coordinate reprojection.