Major improvements to the Jellyfin PostgreSQL Windows installer:
- Added build-installer.ps1 (PowerShell automation)
- Added jellyfin-setup.iss (Inno Setup script) and jellyfin.ico
- Added detailed installer guides and quick start docs
- Fixed startup.json defaults: removed old file, ensured Windows paths
- Updated .gitignore for installer-output and publish profiles
- Installer now supports service install, firewall setup, and PostgreSQL config wizard
- Documentation covers both quick and production-grade workflows
