feat: add active_ab_tests to swap events

[bfullam]

Explanation

This PR updates Unified SwapBridge metrics migration support so legacy and new A/B test payloads can coexist without conflation.

Current state:

• Bridge events already supported legacy ab_tests.
• active_ab_tests needed to be supported in parallel during migration.
• Earlier wiring could make these appear equivalent if the same context was reused.

What changed:

• Added optional active_ab_tests support to bridge-controller metrics event context/payload types.
• In bridge-status-controller, introduced separate activeAbTests context input/storage alongside legacy abTests.
• Updated event tracking resolution so ab_tests and active_ab_tests are handled independently.
• Updated pre-confirmation metrics property generation to accept and emit separate legacy/new test maps.
• Clarified JSDoc/type comments to document why both fields currently exist and how migration is intended.

Why another package was updated:

• bridge-status-controller publishes events through bridge-controller metrics types, so bridge-controller type definitions had to include active_ab_tests to keep typing aligned.

References

• No linked issue.

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

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Note

Low Risk
Low risk: this is additive metrics/type plumbing that keeps legacy ab_tests behavior intact while emitting a new optional active_ab_tests payload when provided.

Overview
Adds dual A/B test context support for SwapBridge metrics. Unified SwapBridge event context/payload types now include optional active_ab_tests alongside legacy ab_tests, with documentation noting the migration window.

Bridge Status Controller now accepts/persists activeAbTests in history and resolves/emits both ab_tests and active_ab_tests independently when tracking post-submission events (including pre-confirmation payload builders). Tests and changelogs are updated accordingly.

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