feat: add daily request limit and refactor access control (#759)

- Add daily request limit per IP in blacklist settings (1-1,000,000/day)
- Refactor access control logic: merge blacklist and rate limit checks
- Remove RATE_LIMIT_API_DAILY_REQUESTS env var, use database config instead
- Move x-custom-auth check earlier in middleware chain
- Add comprehensive English documentation (31 new guide pages)
- Improve code structure and error handling

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Co-authored-by: Claude <noreply@anthropic.com>

vitepress-docs/docs/en/guide/feature/user-oauth2.md

@@ -0,0 +1,26 @@
+# OAuth2 Third-Party Login
+
+> [!WARNING] Note
+> Third-party login will automatically register an account using the user's email (emails with the same address will be considered the same account)
+>
+> This account is the same as a registered account and can also set a password through the forgot password feature
+
+## Register OAuth2 on Third-Party Platforms
+
+### GitHub
+
+- Please first create an OAuth App, then obtain the `Client ID` and `Client Secret`
+
+Reference: [Creating an OAuth App](https://docs.github.com/en/apps/oauth-apps/building-oauth-apps/creating-an-oauth-app)
+
+### Authentik
+
+- [Authentik OAuth2 Provider](https://docs.goauthentik.io/docs/providers/oauth2/)
+
+## Configure OAuth2 in Admin Backend
+
+![oauth2](/feature/oauth2.png)
+
+## Test User Login Page
+
+![oauth2 login](/feature/oauth2-login.png)