[Web UI] Split Monaco chunk, reduce idle list polling, fix axios cancel key

[shangeyao]

Problem

• Monaco editor is bundled into the main chunk, increasing first-load size
• Flink/Spark app list pages poll every 2 seconds even when idle
• Axios cancel keys use only method+url, causing different query params to cancel each other

Proposed solution

• Split monaco-editor into a dedicated Vite chunk
• Use 5s idle / 2s active adaptive polling on app list pages
• Include serialized query params in axios pending request keys

[shangeyao]

Closing because related PR #4407 was closed without merge. Console frontend is being refactored; this work is deferred.