fix(event-form): stabilize page metadata (PPN) acknowledgment hydration

[qiyundai]

Resolves: https://jira.corp.adobe.com/browse/MWPW-193969

Summary

• Apply publishing profile metadata and metadataFieldAcknowledged in a single form update when the metadata catalogue is already loaded; otherwise set pendingProfileAckBackfill and flush acks when the catalogue arrives.
• Replace the profileHydrationTick effect with explicit pending backfill and merge previous ack state when syncing catalogue keys.
• Reset publishingProfileRef and pending backfill when eventId changes so switching events always reloads the profile.
• Normalize ESP responses with publishingProfileFromAssociation so profileId from the association wrapper is kept when the nested profile omits it.
• Validation treats a field as satisfied when acknowledged or when metadata already holds a value (server-backed product selection).

Test plan

• Webinar edit, profile with empty / missing PPN: change another step-1 field, save without opening the PPN picker — should succeed.
• Leave step 1 before profile GET finishes, return, save — should succeed after load.
• New webinar: save still blocked until each catalogue field is explicitly chosen (product or No).
• Edit event with real PPN values from API: save without re-opening pickers — should succeed.

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