Postgres perf, path migration, and shutdown race fixes

- Major query performance boost: replaced correlated subqueries with DistinctBy() in BaseItemRepository, added episode deduplication index, and increased default command timeout to 120s.
- Fixed LibraryMonitor shutdown race: added disposal checks and exception handling in FileRefresher to prevent ObjectDisposedException.
- Added PowerShell and SQL utilities for fixing Linux paths in config files and database; new scripts for WebDir and path migration.
- Auto-fix for WebDir in startup.json on load; new helper scripts and docs.
- Added automated weekly DB performance monitoring scripts and reporting.
- Expanded documentation and README for all fixes, scripts, and migration steps.
- Updated SQL scripts for index creation and diagnostics; improved output handling.
- Updated db-config defaults and added new diagnostic/report files.

reports/weekly/summary_2026-03-05_080020.txt

@@ -0,0 +1,50 @@
+================================================================================
+JELLYFIN DATABASE WEEKLY PERFORMANCE SUMMARY
+================================================================================
+Report Date: 2026-03-05 08:00:21
+Database: jellyfin_testdata at 192.168.129.248
+Week Number: 10
+================================================================================
+
+REPORTS GENERATED:
+ * diagnostics_2026-03-05_080020.txt           : Full diagnostic report
+ * query_analysis_2026-03-05_080020.txt        : Slow query analysis
+ * index_usage_2026-03-05_080020.txt           : Index usage statistics
+ * table_sizes_2026-03-05_080020.txt           : Table size and bloat info
+ * summary_2026-03-05_080020.txt               : This summary
+
+================================================================================
+QUICK HEALTH CHECK:
+================================================================================
+
+To view critical issues check diagnostics file for:
+ * Section 5: TABLES WITH HIGH SEQUENTIAL SCANS
+ * Section 8: UNUSED OR RARELY USED INDEXES
+ * Section 10: SLOWEST QUERIES
+
+To identify slow queries check query_analysis file for:
+ * Section 2: TOP 20 SLOWEST QUERIES (by max execution time)
+ * Section 5: BASEITEMS TABLE QUERIES ANALYSIS
+
+================================================================================
+RECOMMENDED ACTIONS:
+================================================================================
+
+ * Review slow queries taking longer than 10 seconds
+ * Check if new indexes are being utilized
+ * Look for tables with many sequential scans
+ * Monitor cache hit ratio (should be above 95 percent)
+ * Check for tables with high dead tuples percentage (need VACUUM)
+
+================================================================================
+AUTOMATION SETUP:
+================================================================================
+
+To schedule this script weekly via Task Scheduler run Setup-Weekly-Monitor.ps1
+as Administrator. This will create a scheduled task to run every Monday at 6am.
+
+To disable the scheduled task run Setup-Weekly-Monitor.ps1 with -Uninstall flag.
+
+================================================================================
+NEXT REPORT: 03/05/2026 08:00:21.AddDays(7).ToString("yyyy-MM-dd")
+================================================================================