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.

docs/README_UPDATE_SUMMARY.md

@@ -0,0 +1,73 @@
+# README.md Update Summary
+
+## Updated: docs\README.md
+
+### New Sections Added
+
+#### 🛠️ Path Configuration & Fixes
+Added a new dedicated section for path-related configuration and troubleshooting:
+
+- **WEBDIR_ISSUE_COMPLETE_FIX.md** - Complete guide to fixing WebDir path issues
+- **STARTUP_JSON_WEBDIR_FIX.md** - Fix startup.json WebDir configuration
+- **PATH_FIX_GUIDE.md** - Comprehensive path fix guide
+- **LINUX_PATH_ISSUE_SUMMARY.md** - Linux paths on Windows issue summary
+- **FIX_SYSTEM_XML_PATHS.md** - Fix Linux paths in system.xml
+- **POWERSHELL_SCRIPT_FIXED.md** - PowerShell utility script fixes
+
+#### 🔧 Utility Scripts
+Added a new section documenting utility scripts for maintenance and fixes:
+
+**PowerShell Scripts:**
+- **FixJellyfinPaths.ps1** - Fix Linux paths in configuration files (system.xml, encoding.xml, database.xml)
+- **FixStartupJsonWebDir.ps1** - Fix WebDir paths in startup.json files
+
+**SQL Scripts:**
+- **add_presentationuniquekey_index.sql** - Add performance index for episode deduplication queries (fixes 180+ second timeouts)
+- **fix_windows_paths.sql** - Convert Linux paths to Windows paths in database (reference script)
+
+### Documentation Organization
+
+All new documentation has been:
+1. ✅ Properly categorized under relevant sections
+2. ✅ Marked with **(NEW)** tags for easy identification
+3. ✅ Formatted consistently with existing documentation
+4. ✅ Linked with correct relative paths
+
+### Quick Access
+
+All new files can be found under:
+- Documentation: `docs/*.md`
+- PowerShell Scripts: `*.ps1` (root directory)
+- SQL Scripts: `*.sql` (root directory)
+
+### Related Issues Fixed
+
+These documentation files and scripts address:
+1. **WebDir Path Issue** - startup.json created with absolute paths instead of relative "wwwroot"
+2. **Linux Paths on Windows** - Configuration files (system.xml) containing Linux paths on Windows installations
+3. **PostgreSQL Query Timeouts** - Missing performance index causing 180+ second query times
+4. **PowerShell Script Errors** - Syntax issues in path fix utilities
+
+### Usage
+
+For path issues:
+```powershell
+# Fix system.xml paths
+.\FixJellyfinPaths.ps1
+
+# Fix startup.json WebDir
+.\FixStartupJsonWebDir.ps1
+```
+
+For PostgreSQL performance:
+```sql
+-- Run as database user
+psql -U jellyfin -d jellyfin -f add_presentationuniquekey_index.sql
+```
+
+### Notes
+
+- All scripts include safety features (backups, dry-run mode)
+- Documentation includes step-by-step instructions
+- Code changes were already implemented in the source code
+- Scripts are for fixing existing installations