Add toggle button for DEBUG_TB_INTERCEPT_REDIRECTS to debug toolbar UI

### Summary This PR introduces a new toggle button in the Flask Debug Toolbar to dynamically enable or disable the `DEBUG_TB_INTERCEPT_REDIRECTS` setting. ### Changes: - Adds backend route: `/_debug_toolbar/views/toggle_redirect_intercept` to flip the config - Injects current config state into `toolbar.py` → template context - Adds a UI toggle button with real-time label (`Intercept: ON/OFF`) and color state ### Motivation: This improves developer productivity by allowing redirect interception control without restarting the server or modifying config files manually.