Add #hi_* temp table debug output and gate debug paths by @find_high_impact

- Add debug dumps for all 15 #hi_* temp tables when @find_high_impact = 1
  (key tables: #hi_plan_stats, #hi_query_stats, #hi_scored, #hi_output)
- Gate non-high-impact temp table dumps behind @find_high_impact = 0
  to reduce noise when debugging the high impact path
- Use OBJECT_ID guard for #hi_* tables to handle cases where the
  high-impact code errors before creating tables (e.g. Query Store disabled)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: erikdarlingdata