feat: Add indicator code verification API and UI

- Add POST /api/indicator/verifyCode endpoint in Python backend.
- Update IndicatorEditor.vue with Verify Code button and error modal.
- Add i18n support for verification UI.
- Update README files.

quantdinger_vue/src/locales/lang/en-US.js

@@ -621,6 +621,10 @@ const locale = {
   'dashboard.indicator.editor.aiPromptRequired': 'Please enter your idea',
   'dashboard.indicator.editor.aiGenerateSuccess': 'Code generated successfully',
   'dashboard.indicator.editor.aiGenerateError': 'Code generation failed, please try again later',
+  'dashboard.indicator.editor.verifyCode': 'Verify Code',
+  'dashboard.indicator.editor.verifyCodeSuccess': 'Verification Passed',
+  'dashboard.indicator.editor.verifyCodeFailed': 'Verification Failed',
+  'dashboard.indicator.editor.verifyCodeEmpty': 'Code cannot be empty',
   'dashboard.indicator.guide.title': 'Python Indicator & Strategy Development Guide',
   'dashboard.indicator.guide.intro': 'This platform supports writing custom technical indicators and trading signals using Python. The system includes built-in pandas and numpy data analysis libraries. You can use standard DataFrame operations to process K-line data and draw charts or mark buy/sell signals.',
   'dashboard.indicator.guide.section1.title': '1. Runtime Environment & Predefined Variables',