Create theme dir if needed (#49)

- Use Path.Combine throughout
- Update theme versions
- Update generator version

src/MyWebLog/Handlers/Admin.fs

@@ -399,8 +399,11 @@ module Theme =
                     let! _ = loadFromZip themeId stream data
                     do! ThemeAssetCache.refreshTheme themeId data
                     TemplateCache.invalidateTheme themeId
+                    // Ensure the themes directory exists
+                    let themeDir = Path.Combine(".", "themes")
+                    if not (Directory.Exists themeDir) then Directory.CreateDirectory themeDir |> ignore
                     // Save the .zip file
-                    use file = new FileStream($"./themes/{themeId}-theme.zip", FileMode.Create)
+                    use file = new FileStream(Path.Combine(".", "themes", $"{themeId}-theme.zip"), FileMode.Create)
                     do! themeFile.CopyToAsync file
                     do! addMessage ctx
                             { UserMessage.Success with
@@ -435,7 +438,7 @@ module Theme =
         | _ ->
             match! data.Theme.Delete (ThemeId themeId) with
             | true ->
-                let zippedTheme = $"./themes/{themeId}-theme.zip"
+                let zippedTheme = Path.Combine(".", "themes", $"{themeId}-theme.zip")
                 if File.Exists zippedTheme then File.Delete zippedTheme
                 do! addMessage ctx { UserMessage.Success with Message = $"Theme ID {themeId} deleted successfully" }
                 return! all next ctx