🚀 feat(frontend): add robust boolean handling across settings pages

Summary
-------
1. Introduced a reusable `toBoolean` utility (`web/src/helpers/boolean.js`) that converts
   strings (`'true'/'false'`, `'1'/'0'`), numbers, and native booleans to a proper boolean.
2. Re-exported `toBoolean` via `web/src/helpers/index.js` for simple one-line imports.

Refactors
---------
• Systematically replaced all legacy `item.value === 'true'` checks with `toBoolean(item.value)` in
  the following components:
  – `SystemSetting.js`
  – `OperationSetting.js`
  – `PaymentSetting.js`
  – `RatioSetting.js`
  – `RateLimitSetting.js`
  – `ModelSetting.js`
  – `DrawingSetting.js`
  – `DashboardSetting.js`
  – `ChatsSetting.js`

• Unified import statements to
  `import { …, toBoolean } from '../../helpers';`
  removing redundant `../../helpers/boolean` paths.

Why
---
SQLite sometimes returns `1/0` or boolean literals instead of the string `'true'/'false'`, causing
checkbox states to reset on page reload. The new utility guarantees consistent boolean parsing,
fixing the issue across all environments (SQLite, MySQL, etc.) while improving code clarity.

web/src/components/settings/SystemSetting.js

@@ -17,6 +17,7 @@ import {
   removeTrailingSlash,
   showError,
   showSuccess,
+  toBoolean,
 } from '../../helpers';
 import axios from 'axios';
 import { useTranslation } from 'react-i18next';
@@ -106,7 +107,7 @@ const SystemSetting = () => {
           case 'LinuxDOOAuthEnabled':
           case 'oidc.enabled':
           case 'WorkerAllowHttpImageRequestEnabled':
-            item.value = item.value === 'true';
+            item.value = toBoolean(item.value);
             break;
           case 'Price':
           case 'MinTopUp':