fix: handle non-SELECT read queries (SHOW, DESCRIBE, EXPLAIN) in run_sql tool

[nagasumanthila]

Problem

The run_sql tool currently determines query type using only the first SQL keyword and treats only "SELECT" queries as returning data. However, several SQL commands such as SHOW, DESCRIBE / DESC, and EXPLAIN also return tabular result sets. These are incorrectly treated as data manipulation queries, resulting in misleading responses like "Query executed successfully. X row(s) affected."

Solution

• Added support for additional read query types: SELECT, SHOW, DESCRIBE, DESC, EXPLAIN, WITH
• Added comments explaining why these queries are treated as read queries

Result

• Non-SELECT read queries now correctly return tabular data
• Prevents hallucinations caused by missing schema information