Add query texts to pg_stat_statements dashboard table

Description

The pg_stat_statements detailed table view currently only shows Query IDs, which are numeric identifiers that are difficult to interpret without context.

Requested Feature

Add a "Query Text" column to the detailed table view in the Query Performance Analysis (top-N) dashboard that shows the actual SQL query text for each query ID.

Implementation Notes

• Query texts should be truncated to ~150 characters for display
• Query texts are stored in the pgss_queryid_queries table in the PostgreSQL sink database
• The Flask backend needs to be updated to fetch query texts and include them in the CSV output