Schema Mismatch: openalex.topics missing 'siblings' column

[Yi-Wu-3452]

Description: The PostgreSQL schema for the openalex.topics table is missing the siblings column, which is present in the current OpenAlex CSV snapshots (topics.csv.gz).

This results in a "copy" error when attempting to load the data using psql.

Steps to Reproduce:

1. Create the openalex.topics table using the standard openalex-pg-schema.sql(which defines 15 columns).
2. Attempt to import the data from the official topics.csv.gz file using the \copy command.

Observed Error:

CONTEXT: COPY topics, line 2: "https://openalex.org/T10001,Geological and Geochemical Analysis, ..."

Technical Details:

• CSV Column Count: 16 columns (the 16th being siblings).
• DDL Column Count: 15 columns.
• Sample Data for siblings: A semi-colon separated list or JSON-formatted string of related topic keywords/URLs (e.g., Zircon; Geochronology; Tectonics; ...).