Story: Validate and reject invalid WKT representations #13

Goal

Complete WKT decoding validation by systematically rejecting malformed, structurally invalid, unsupported, or incomplete representations.

Validation must be strict: invalid input must never be silently corrected, partially decoded, truncated, or interpreted through an unsupported extension.

Acceptance criteria

• Invalid WKT syntax is explicitly rejected.
• Unknown or unsupported geometry types are explicitly rejected.
• Invalid coordinate syntax and arity are rejected.
• Invalid geometry structures are rejected.
• Inconsistent coordinate dimensions are rejected.
• Missing or unexpected tokens are rejected.
• Unexpected trailing content is rejected.
• Unsupported extensions are rejected rather than implicitly accepted.
• Failures use the appropriate public decoder exceptions.
• Unit tests include positive and negative cases covering the complete supported WKT scope.
• The standard test and quality suites pass.

Out of scope

• Geometry repair or normalization.
• Semantic transformations.
• EWKT-specific validation.
• Coordinate reprojection.