fix: remove legacy SDK dependency

[jbiskur]

Summary

• move data-pump to Flowcore SDK 6.1.0
• remove legacy Scenario and GraphQL code from the installed runtime tree

Verification

• bun build and typecheck
• 103 tests pass
• clean packed install imports FlowcoreDataPump
• packed dependency tree contains SDK 6.1.0 only
• executable, declaration, and source-map scan finds no legacy GraphQL or Scenario code

[jbiskur]

Downstream CLI smoke verified with a local Core 6 assembly: the CLI selected @flowcore/cli-plugin-core 6.0.1, resolved @flowcore/data-pump 0.23.1 with SDK 6.1.0, and completed an authenticated read-only stream from now with zero events and exit 0. The changed Core/config/data-pump code tree contains no legacy GraphQL or Scenario code. This also exposed a required downstream Core compiler bump from TypeScript 5.4.4 to 5.9.3 for current NATS declarations; that fix belongs in the Core PR.