- Add 'brief' field to GenerateContentRequest schema
- Pass brief from router to generate_post_text service
- Inject brief as mandatory instructions in LLM prompt with highest priority
- Return structured error when LLM provider/API key not configured
- Show dedicated warning banner with link to Settings when API key missing
Fixes: content ignoring editorial brief, unhelpful API key error messages
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
- Redesign Settings: Testi, Immagini, Video, Voiceover — sezioni separate
- Ogni sezione ha dropdown provider + API key + campo opzionale modello
- Opzione "Personalizzato" con campo Base URL libero per qualsiasi servizio
- LLM: aggiunto OpenRouter + provider custom OpenAI-compatible
- Backend: OpenAICompatibleProvider unifica OpenAI/OpenRouter/custom
- Router content: passa llm_base_url a get_llm_provider
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>