Add automatic PostgreSQL database creation and migration

- Added Jellyfin.Database.Providers.Postgres project with full EF Core migration support for PostgreSQL.
- Implemented automatic database creation and privilege assignment on startup.
- Generated initial migration and model snapshot for PostgreSQL schema.
- Updated build, test, and dependency files to include PostgreSQL provider and Npgsql packages.
- Added PowerShell script for generating and testing PostgreSQL migrations.
- No changes to application logic outside database provider/migration infrastructure.

Emby.Server.Implementations/obj/project.nuget.cache

@@ -1,6 +1,6 @@
 {
   "version": 2,
-  "dgSpecHash": "CU3WcVn0qXE=",
+  "dgSpecHash": "zPBm14Az/RI=",
   "success": true,
   "projectFilePath": "E:\\Projects\\pgsql-jellyfin\\Emby.Server.Implementations\\Emby.Server.Implementations.csproj",
   "expectedPackageFiles": [
@@ -63,6 +63,8 @@
     "C:\\Users\\wjones\\.nuget\\packages\\microsoft.win32.systemevents\\9.0.2\\microsoft.win32.systemevents.9.0.2.nupkg.sha512",
     "C:\\Users\\wjones\\.nuget\\packages\\nebml\\1.1.0.5\\nebml.1.1.0.5.nupkg.sha512",
     "C:\\Users\\wjones\\.nuget\\packages\\newtonsoft.json\\13.0.4\\newtonsoft.json.13.0.4.nupkg.sha512",
+    "C:\\Users\\wjones\\.nuget\\packages\\npgsql\\10.0.0\\npgsql.10.0.0.nupkg.sha512",
+    "C:\\Users\\wjones\\.nuget\\packages\\npgsql.entityframeworkcore.postgresql\\11.0.0-preview.1\\npgsql.entityframeworkcore.postgresql.11.0.0-preview.1.nupkg.sha512",
     "C:\\Users\\wjones\\.nuget\\packages\\playlistsnet\\1.4.1\\playlistsnet.1.4.1.nupkg.sha512",
     "C:\\Users\\wjones\\.nuget\\packages\\polly\\8.6.5\\polly.8.6.5.nupkg.sha512",
     "C:\\Users\\wjones\\.nuget\\packages\\polly.core\\8.6.5\\polly.core.8.6.5.nupkg.sha512",