Add a language selector to the System Settings page supporting English,
Japanese, and Chinese. The i18n dictionary already contained zh
translations but lacked the UI to switch languages.
Changes:
- html/i18n.js: add sys_language key to en/ja/zh
- html/system.html: add language selector dropdown
- html/system.js: add changeLang() and selector initialization
- tools/httpd_sim.c: fix cookie parsing for multi-cookie headers;
fix Set-Cookie response (missing Path=/, missing \r\n\r\n);
add SO_REUSEADDR for faster port reuse