Enhance JSONL endpoint with tile metadata and error information

[MisterGC]

Motivation

The current GeoJSON/JSONL endpoint (POST /tiles with Accept: application/jsonl) returns only basic GeoJSON FeatureCollections without tile-level metadata. This limits automated processing capabilities:

• Cannot determine which mapget tile a JSONL line belongs to
• No error information for automated retry logic
• Missing timestamp/TTL for cache validation

Proposed Changes

Enhance the JSONL response format to include additional metadata per tile:

Field	Type	Description
mapgetTileId	integer	The mapget tile ID (64-bit decimal)
mapgetLayerId	string	Layer identifier within the map
mapId	string	Map identifier
idPrefix	object	Common ID parts shared by all features (optional)
timestamp	string	ISO 8601 timestamp when tile was created
ttl	integer	Time-to-live in milliseconds (optional)
error	object	Error info if tile creation failed (optional)
error.code	integer	Numeric error code (HTTP status, DB error, etc.)
error.message	string	Human-readable error message

Note: Using mapgetTileId and mapgetLayerId prefixes to avoid confusion with map format-specific terms.

Implementation

• Add errorCode field to TileLayer class
• Enhance TileFeatureLayer::toJson() to include all metadata
• Update Python bindings
• Update documentation
• Add unit tests