Adopts the approach from #1330 (thanks @duncan-daydream) on top of the v0.8.40
Swift import fix: _import_swift returns (id,label) module pairs, the extractor
materializes a type=module anchor node per import, and _disambiguate_colliding_node_ids
exempts type=module nodes so the same module imported from N files collapses to
one shared node (enables reverse traversal "what imports CoreKit"). The --no-cluster
writer now dedupes nodes by id and edges to match the clustered build_from_json path.
Replaces the interim _import_label/synthesize_import_module_nodes mechanism.
Adds tests/test_swift_import_resolution.py (cross-file collapse, build survival)
and dedupe_nodes coverage. Refs #1327, #1330.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
