fix(clickhouse): drug synonyms/tradeNames are {label, source} struct arrays

[d0choa]

Summary

drug_molecule's synonyms and tradeNames fields changed from array<string> to array<struct<label, source>> (opentargets/pts#142, tracking issue opentargets/issues#4414) — each name now carries provenance (ChEMBL, or AACT for names mined from clinical trials).

POS ingests output/drug_molecule directly into the drug_log ClickHouse table via config/clickhouse/schema/drug.sql, so the column DDL must match the parquet. Loading the new struct arrays into Array(String) columns would fail.

What changed

config/clickhouse/schema/drug.sql — synonyms and tradeNames change from Array(String) to Array(Tuple(label String, source String)), mirroring the existing crossReferences tuple. The final drug table (scripts/drug.sql, SELECT *) inherits the new types, so nothing else changes.

Scope (verified)

This is the only POS consequence:

• OpenSearch — there's no drug_molecule index; the drug dataset goes only to ClickHouse. search_drug is built from the flattened search dataset (.label strings, schema unchanged); indication doesn't carry these fields.
• BigQuery / release — parquet is copied / auto-detected; no explicit drug schema references these fields.
• No src/ Python or other ClickHouse script references drug synonyms/tradeNames.

ClickHouse matches Tuple elements to the parquet struct positionally; the parquet order is {label, source} (label first), which the DDL matches — consistent with the existing crossReferences tuple.