fix(reactome): preserve unmatched selection schema

[FuqingZh]

Summary

• Project the publication-backed single-selection unmatched frame to the public input_id schema.
• Add source/publication regression coverage across four namespaces and three selection modes.

Root cause

Reactome selection normalization retains the internal lookup_id column. The publication-backed single-selection iterator passed that internal column through while declaring the public schema as only input_id, causing selection.unmatched_ids().collect() to raise a Polars SchemaError.

Validation

• BIOEXTRACT_TEST_THREADS=1 pdm run check
• 848 tests passed in 305.44s
• Focused Reactome, cross-resource publication, lint, format, and direct formal-publication readback checks passed.