feat: add /api/generate_dm endpoint (DM personalizzati, guardrail dedicati)

fix: drop gpt-oss-120b (reasoning model), swap to Llama 3.3 + Qwen 2.5

fix: gradio 5.x (audioop removed in Python 3.13)

fix: gradio 5.x (audioop removed in Python 3.13)

Initial version: IG comment generator (HF Inference Providers)

initial commit