Add action-based survey targeting

🚨 IMPORTANT

This issue is likely user-facing in the main PostHog app, see surveyVersionRequirements.ts. If you delete or close this issue, be sure to update the version requirements list here.

Summary

The posthog-flutter SDK does not support action-based survey targeting.

Current State

• Flutter delegates survey handling to the native iOS and Android SDKs
• Neither posthog-ios nor posthog-android currently support action-based survey targeting

Expected Behavior

When a survey is configured with action-based targeting (survey.conditions.actions.values), the Flutter SDK should:

1. Match captured events against the configured actions
2. Only show the survey when a matching action is triggered

This requires the underlying native SDKs (posthog-ios and posthog-android) to implement action-based targeting first.

Dependencies

• https://github.com/PostHog/posthog-ios/issues/451
• https://github.com/PostHog/posthog-android/issues/394

Reference Implementation

See posthog-js browser: packages/browser/src/extensions/surveys/ActionMatcher.ts

Tracking

This is tracked in the survey SDK feature parity issue: https://github.com/PostHog/posthog/issues/45658

This issue was generated by Claude using the /survey-sdk-audit skill.

First check the linked posthog-ios and posthog-android issues, since Flutter delegates survey handling to those SDKs. Compare the required behavior with packages/browser/src/extensions/surveys/ActionMatcher.ts and review frontend/src/scenes/surveys/surveyVersionRequirements.ts. Done means matching configured actions causes the survey to appear only after a matching event, once native support exists.