feat(autofix): Register autofix-retry-from-step feature flag

Add a new Flagpole feature flag to gate "Retry from step" buttons on
Autofix v3 cards. This is primarily useful for local Seer testing,
allowing developers to re-run individual autofix steps without
restarting the entire flow.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: isaacwang-sentry

src/sentry/features/temporary.py

@@ -318,6 +318,8 @@ def register_temporary_features(manager: FeatureManager) -> None:
     manager.add("organizations:autofix-on-explorer", OrganizationFeature, FeatureHandlerStrategy.FLAGPOLE, api_expose=True)
     # Enable Autofix to use Seer Explorer V2 designs
     manager.add("organizations:autofix-on-explorer-v2", OrganizationFeature, FeatureHandlerStrategy.FLAGPOLE, api_expose=True)
+    # Enable "Retry from step" buttons on Autofix v3 cards (for local Seer testing)
+    manager.add("organizations:autofix-retry-from-step", OrganizationFeature, FeatureHandlerStrategy.FLAGPOLE, api_expose=True)
     # Enable Seer Workflows in Slack
     manager.add("organizations:seer-slack-workflows", OrganizationFeature, FeatureHandlerStrategy.FLAGPOLE, api_expose=True)
     # Enable new compact issue alert UI in Slack