fix: 修复返回给前端的 totalTokens 为0的问题并提供示例 .env

backend/.env

@@ -0,0 +1,17 @@
+# ---- AI 服务 API Key ----
+CAMTALK_AI_LLM_API_KEY=sk-ws-H.REHELLY.C4s3.MEUCIQCRee37XWEKp2szaxVLFDtR1rxNNsf372zMvCR0Xl6UvQIgZgvhRTvaa1FmhbCQJgaHu4Jny29AQkn01-3hX9CWBOg
+CAMTALK_AI_STT_API_KEY=tp-c9e7scwfx94qvqyhpnahnw8uaiya01za2qzvg4xe24rp3xiv
+CAMTALK_AI_TTS_API_KEY=tp-c9e7scwfx94qvqyhpnahnw8uaiya01za2qzvg4xe24rp3xiv
+
+# ---- 可选覆盖（默认值见 config.yaml）----
+# CAMTALK_AI_LLM_MODEL=qwen3-vl-plus
+# CAMTALK_AI_LLM_ENDPOINT=https://api.openai.com/v1
+# CAMTALK_AI_LLM_TIMEOUT=10
+# CAMTALK_AI_STT_ENDPOINT=wss://api.deepgram.com/v1/listen
+# CAMTALK_AI_TTS_ENDPOINT=https://api.openai.com/v1
+# CAMTALK_AI_TTS_VOICE=alloy
+# CAMTALK_AI_TTS_SPEED=1.0
+# CAMTALK_AI_TTS_TIMEOUT=5
+
+# ---- 应用 ----
+# APP_ENV=dev