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

startup.json.example

@@ -20,8 +20,8 @@
       "ConfigDir": "/etc/jellyfin",
       "CacheDir": "/var/cache/jellyfin",
       "LogDir": "/var/log/jellyfin",
-      "TempDir": "/var/tmp/jellyfin",
-      "WebDir": "/usr/share/jellyfin/web"
+      "TempDir": "/tmp/jellyfin",
+      "WebDir": "/usr/share/jellyfin/wwwroot"
     }
   },
 
@@ -32,7 +32,7 @@
       "CacheDir": "D:\\Cache\\Jellyfin",
       "LogDir": "C:\\ProgramData\\Jellyfin\\logs",
       "TempDir": "D:\\Temp\\Jellyfin",
-      "WebDir": "C:\\Program Files\\Jellyfin\\web"
+      "WebDir": "C:\\ProgramData\\Jellyfin\\wwwroot"
     }
   },
 
@@ -43,7 +43,7 @@
       "CacheDir": "./cache",
       "LogDir": "./logs",
       "TempDir": "./temp",
-      "WebDir": "./web"
+      "WebDir": "./wwwroot"
     }
   },