Fix API authentication errors returning HTML instead of JSON

[Copilot]

When unauthenticated users attempt deletion requests, the API returns HTML error pages instead of JSON. The frontend cannot parse HTML as JSON, triggering catch blocks that show "网络错误或服务器异常，请稍后再试" instead of the actual error message "需要登录".

Changes

Modified middleware/error_display.js to detect API requests and return JSON responses:

export default (err, req, res, next) => {
	const isJsonRequest = req.path.startsWith('/api/') ||
	                      req.xhr || 
	                      req.headers.accept?.includes('application/json');
	
	if (isJsonRequest) {
		return res.json(makeResponse(false, { message: err.message }));
	}
	
	res.render('system/error.njk', { title: "错误", error_message: err.message });
}

Impact

Fixes authentication error handling for all API endpoints using requireLogin or requireAdmin middleware:

• Deletion requests (/api/deletion/:type/:id)
• Notification endpoints (/notification/api, /notification/:id/read, /notification/read-all)
• Admin API endpoints (/admin/api/*)

Users now see "需要登录" instead of generic network errors when attempting authenticated actions while logged out.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• spider-benben.imken.dev
  • Triggering command: node -e import('./app.js').then(() => console.log('OK')).catch(e => console.error(e)) (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

未登录时申请删除会提示「网络错误或服务器异常，请稍后再试
」而不是「需要登录」，请修复这个问题。

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