Jellyfin 11.0.0-PostgreSQL PREVIEW: version bump & defaults

- Update version to 11.0.0-PostgreSQL-PREVIEW in assemblies, installer, and build scripts
- Default web directory is now "wwwroot" across all platforms
- Configuration manager now creates .example files if missing
- Set PostgreSQL as default database with sensible options
- Postgres provider ensures database exists before table checks
- Add docs for marker conflict fixes and startup.json path issues
- Version string in logs/UI uses informational version
- Installer output filename and wizard show PREVIEW suffix
- Documentation summarizes version bump and verification steps

build-installer.ps1

@@ -3,12 +3,12 @@
 
 param(
     [Parameter(Mandatory=$false)]
-    [string]$Version = "11.0.0",
-    
+    [string]$Version = "11.0.0-PostgreSQL-PREVIEW",
+
     [Parameter(Mandatory=$false)]
     [ValidateSet("Release", "Debug")]
     [string]$Configuration = "Release",
-    
+
     [Parameter(Mandatory=$false)]
     [switch]$SkipBuild
 )