Use GEFF track_node_props metadata for tracklet/lineage key round-tripping

[cmalinmayor]

Problem

When exporting to GEFF via export_to_geff, funtracks does not set track_node_props in the GEFF metadata. When importing from GEFF via import_from_geff, funtracks does not read track_node_props to determine which node property stores tracklet/lineage IDs.

This means:

1. Export: The GEFF file has no metadata indicating which property is the tracklet/lineage ID, even though the data is present as a node property.
2. Import: If a GEFF file has a non-standard tracklet key (e.g., older files with "track_id" instead of "tracklet_id"), the fuzzy name inference can mismatch it (e.g., "track_id" gets mapped to "seg_id"), causing tracklet IDs to be silently recomputed.

Proposed Changes

Export (geff/_export.py)

• Set track_node_props on the GeffMetadata using tracks.features.tracklet_key and tracks.features.lineage_key.

Import (geff/_import.py)

• In GeffTracksBuilder.read_header() or infer_node_name_map(), read metadata.track_node_props and use it to seed the name map for tracklet/lineage keys (e.g., {"tracklet_id": "track_id"}) before fuzzy matching runs.
• Since track_node_props is optional in the GEFF spec, this should be a best-effort enhancement — fall back to existing fuzzy matching when absent.

Context

Discovered during review of the fix-tracklet-attr-forwarding branch. Currently accepted that old GEFFs with "track_id" will recompute tracklet IDs unless the user provides an explicit node_name_map. This issue would improve that experience by leveraging GEFF metadata when available.