Re-type workflow summary once at flow start ingress to avoid per-poll deserialization - #225

Pull Request type

• [ x] Bugfix
• Feature
• Refactoring (no functional changes, no api changes)
• Build related changes (Please run ./gradlew build --write-locks to refresh dependencies)
• Other (please describe):

NOTE: Please remember to run ./gradlew spotlessApply to fix any format violations.

Changes in this PR

When a flow starts on a node that does not own its group, the workflow summary is sent over REST and deserialized into an untyped Map, so flow.getInput() holds a LinkedHashMap instead of a WorkflowSummary. Every step poll then re-runs a full Jackson convertValue over the whole summary and discards the result, which shows up as significant CPU and allocation/GC overhead on the step execute path, growing with workflow size.

This change re-materializes the summary into a typed WorkflowSummary once at the flow-start REST ingress, so downstream reads take the cheap cast path instead of converting on every poll.