[front] Record publishing agent on Frames v2 publications

[davidebbo]

Summary

useVisualizationRetry's canRetry gate (and therefore the "Ask agent to fix" button on a Frame runtime error) requires useCaseMetadata.lastEditedByAgentConfigurationId to be set. The legacy Frame publish path (publishFrame) has always recorded this field on publish. The Frames v2 publish/activation path never did: publishFrameFromSource received publishedByAgentConfigurationId from the sandbox /publish route but dropped it on the frame.isFrameV2 branch instead of forwarding it into publishFrameV2FromSource, so it never reached activateFramePublication / FileResource.setActiveFramePublication, which writes useCaseMetadata.

As a result, no Frames v2 file ever got lastEditedByAgentConfigurationId set, so "Ask agent to fix" could never appear for a Frames v2 runtime error, in any conversation.

This threads publishedByAgentConfigurationId through the full v2 activation chain (publishFrameFromSource → publishFrameV2FromSource → buildAndPublishFramePublication → publishFramePublication → activateFramePublication → FileResource.setActiveFramePublication) and has the last step write lastEditedByAgentConfigurationId into useCaseMetadata, matching the legacy path's behavior.

Also adds a code contract on setActiveFramePublication documenting this invariant, since it was previously undocumented and silently broken.

Test plan

• npx tsgo --noEmit passes
• npm run format:changed / biome check passes
• cc-check format / cc-check list validate the new contract
• Manually verified locally: republished a Frames v2 file with a runtime error and confirmed the "Ask agent to fix" button now appears