Add quoteIdentifier() function to safely quote PostgreSQL identifiers
following PostgreSQL's quoting rules (wrap in double quotes, escape
internal quotes by doubling).
This provides defense-in-depth for the CREATE DATABASE statement,
complementing the existing validateDBName() input validation.
Changes:
- Add quoteIdentifier() function with proper escaping
- Use quoted identifier in CREATE DATABASE statement
- Add comprehensive unit tests for quoteIdentifier()
