PHP 7.4 OpenAI Chat Widget — Responses API (.env)
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Endpoint: POST https://api.openai.com/v1/responses
Body: {
  "model": "...",
  "input": [
    {"role":"system","content":[{"type":"text","text":"..."}]},
    {"role":"user","content":[{"type":"text","text":"..."}]}
  ],
  "temperature": 0.7
}
Output: gabungkan semua `output[].content[].text` (atau gunakan `output_text` bila ada).

Langkah:
1) .env -> isi OPENAI_API_KEY & DB_*
2) Import db.sql ke MySQL
3) Jadikan `public/` sebagai webroot Apache
4) Buka http://localhost/chat/public/