- TemplateImageGenerator->render() now returns a typed array shape
{path: string, source_meta: array} instead of a one-off RenderedSlide
DTO. Single internal callsite, no need for a dedicated class.
- Drop the `?? 'en'` fallback on $workspace->content_language in 6
callsites: the column has a NOT NULL default of 'en' at the DB level,
so the null coalesce was dead code.
- WorkspaceFactory now seeds content_language, brand_tone, brand_font
and image_style explicitly so make() (no DB persist) produces a
complete model — DB defaults aren't applied until create().