fix: 补齐 99543c9 遗漏的内容改动（该提交的 git add 因 pathspec 报错未生效）

上一个 refactor 提交只落到 main.py 的重命名，端口与路径的实际改动漏掉了，此提交补齐：
- source/main.py: PIXIV_BACKEND 9088->9007, BILIBILI_BACKEND 19990->9006, port 9888->9008
- nginx/openapi.rrrosmontis.icu.conf: 3 处 proxy_pass -> 127.0.0.1:9008
- systemd/openapi.service: WorkingDirectory/ExecStart 同步为 source/

source/main.py

@@ -1,8 +1,8 @@
 from aiohttp import web, ClientSession, ClientTimeout
 
 
-PIXIV_BACKEND = "http://127.0.0.1:9088"
-BILIBILI_BACKEND = "http://127.0.0.1:19990"
+PIXIV_BACKEND = "http://127.0.0.1:9007"
+BILIBILI_BACKEND = "http://127.0.0.1:9006"
 
 
 async def handle_pixiv(request):
@@ -52,4 +52,4 @@ app.router.add_get("/pixiv/get_image", handle_pixiv)
 app.router.add_get("/bilibili/get_video", handle_bilibili)
 
 if __name__ == "__main__":
-    web.run_app(app, host="127.0.0.1", port=9888)
+    web.run_app(app, host="127.0.0.1", port=9008)