feat(core): persist compaction model and provider state

[rekram1-node]

Issue for this PR

None.

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

Persist optional model and providerState on completed compactions. New compactions record the resolved model and the accepted response's state, using the route's provider-metadata namespace. Rejected-attempt state is discarded. Core/client projections retain the fields, and sanitized exports redact provider state.

Old checkpoints remain readable without migrations or model guessing. No prompt, retained-history, or native-replay changes.

Minimal diff: 6 handwritten production files (23 added lines), 3 existing test files, and 2 generated client files. No new files.

How did you verify your code works?

• 282 focused Core tests and all 146 Client tests passed.
• Core, Client, Schema, Protocol, and Server typechecks passed.
• Regenerated clients/OpenAPI documentation; generated-documentation and diff checks passed.
• The previous Linux/Windows E2E failures were stale activity-control and warning-icon assertions. Updated the branch with the existing v2 fix from test(app): align timeline assertions with activity controls #47089 rather than adding unrelated UI changes here.
• All 28 tests across the three previously failing E2E files now pass locally against a production build with retries disabled.

Screenshots / recordings

Not applicable; no UI behavior changes.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR