Fix SQL injection vulnerability in Redshift fetch_table

[shaikjr]

The fetch_table function used an f-string to build the SQL query, allowing the table name to be injected directly into the query. This fixes it by using psycopg2.sql.Identifier for safe identifier composition and parameterized queries for the LIMIT value. Also added a basic validation check on the table name.

Also removed two stray Windows Zone.Identifier files that were accidentally tracked.

[harshitboots]

Nice security improvement overall switching from f-string SQL to psycopg2.sql.Identifier + parameterized LIMIT is the right fix.
One concern: the new table.replace('_', '').isalnum() validation may reject valid Redshift/Postgres table references like public.users. Since sql.Identifier already handles safe escaping, can we either remove that validation or update it to support schema-qualified names safely?

[shaikjr]

Good catch the validation was overly restrictive for schema-qualified names. Since psycopg2.sql.Identifier already safely handles identifier escaping, I’ll remove the custom validation to avoid blocking valid table references like public.users.