docs: update deployment env and runtime docs for convex qwen minio

.env.example

@@ -1,10 +1,20 @@
 # Runtime
 NODE_ENV=production
 PORT=3000
-STATE_FILE_PATH=/data/state.json
 LOG_LEVEL=info
 APP_BASE_URL=https://xartaudio.example.com
 
+# Better Auth
+BETTER_AUTH_SECRET=replace-me
+BETTER_AUTH_BASE_PATH=/api/auth
+BETTER_AUTH_DEV_PASSWORD=replace-me
+
+# Convex
+CONVEX_DEPLOYMENT_URL=https://your-deployment.convex.cloud
+CONVEX_AUTH_TOKEN=
+CONVEX_STATE_QUERY=state:getLatestSnapshot
+CONVEX_STATE_MUTATION=state:saveSnapshot
+
 # Webhook secrets
 X_WEBHOOK_SECRET=replace-me
 POLAR_WEBHOOK_SECRET=replace-me
@@ -18,19 +28,22 @@ POLAR_ACCESS_TOKEN=replace-me
 POLAR_SERVER=production
 POLAR_PRODUCT_IDS=prod_123
 
-# TTS (OpenAI-compatible)
-TTS_API_KEY=replace-me
-TTS_BASE_URL=
-TTS_MODEL=gpt-4o-mini-tts
-TTS_VOICE=alloy
+# Qwen3 TTS
+QWEN_TTS_API_KEY=replace-me
+QWEN_TTS_BASE_URL=https://dashscope-intl.aliyuncs.com/compatible-mode/v1
+QWEN_TTS_MODEL=qwen-tts-latest
+QWEN_TTS_VOICE=Cherry
+QWEN_TTS_FORMAT=mp3
 
-# S3-compatible object storage
-S3_BUCKET=replace-me
-S3_REGION=us-east-1
-S3_ENDPOINT=
-S3_ACCESS_KEY_ID=replace-me
-S3_SECRET_ACCESS_KEY=replace-me
-S3_SIGNED_URL_TTL_SEC=3600
+# MinIO object storage
+MINIO_ENDPOINT=minio.example.com
+MINIO_PORT=443
+MINIO_USE_SSL=true
+MINIO_BUCKET=replace-me
+MINIO_REGION=us-east-1
+MINIO_ACCESS_KEY=replace-me
+MINIO_SECRET_KEY=replace-me
+MINIO_SIGNED_URL_TTL_SEC=3600
 
 # Credit policy
 BASE_CREDITS=1