fix(store): support LIST columns in parted fill

[singaraiona]

Summary

• construct zero-row RAY_LIST columns with ray_list_new(0) during .db.parted.fill
• preserve the original fill failure code and message, with table and partition context
• add C and Rayfall regression coverage for empty nested-column round-trips, fill/read-back, idempotency, and corrupt-template error fidelity

Root cause

empty_table_like passed every dynamic column type to ray_vec_new. RAY_LIST is type code 0, while ray_vec_new only accepts positive concrete vector types, so gap-filling a table with a LIST column failed. The fill loop then replaced the underlying error with a generic io error.

Impact

Parted roots can now gap-fill tables containing LIST columns, including LIST-of-DICT data. When fill fails for another reason, callers receive the real error category and actionable table/partition context.

Validation

• debug ASan/UBSan build: make -j2
• focused C regression: RAYFORCE_CORES=2 ./rayforce.test -f splay_empty_list_column_roundtrip
• focused Rayfall regression: RAYFORCE_CORES=2 ./rayforce.test -f db_parted_fill
• full sanitizer suite: make test TEST_CORES=2 — 3,677/3,677 passed

Fixes #401