chore: left-shift insight filtering and pagination into EvalClient

[nborges-aws]

Description

Move filtering and pagination handling logic into EvalClient

• Adds dedicated listBatchInsights API -- backed by listBatchEvaluations
• Scans batch eval pages until it collects correct number of Insight jobs (following gateway pattern)
• Preserves continuation tokens without skipping Insights jobs at service-page boundaries
• update imperative and TUI callers to consume pre-filtered insights
• Adds dedicated BatchInsightsPicker and restores BatchEvaluationsPicker to eval-only interface

This is a follow up to PR #2078. Along with improving filtering/pagination handling, this PR scaffolds a standalone insights API and picker. This creates an existing degree of separation between insights and evaluations, proofing our code for any divergence between the two in the future.

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update
• Other (please describe):

Testing

How have you tested the change?

• bun run test (1805 pass, 0 fail)
• I ran npm run test:unit and npm run test:integ
• I ran npm run typecheck
• I ran npm run lint
• If I modified src/assets/, I ran npm run test:update-snapshots and committed the updated snapshots

Checklist

• I have read the CONTRIBUTING document
• I have added any necessary tests that prove my fix is effective or my feature works
• I have updated the documentation accordingly
• I have added an appropriate example to the documentation to outline the feature, or no new docs are needed
• My changes generate no new warnings
• Any dependent changes have been merged and published

---

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terms of your choice.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.37%. Comparing base (768ef10) to head (1b61a60).

Additional details and impacted files

@@            Coverage Diff            @@
##           refactor    #2092   +/-   ##
=========================================
  Coverage     97.36%   97.37%           
=========================================
  Files           410      411    +1     
  Lines         24796    24879   +83     
=========================================
+ Hits          24142    24225   +83     
  Misses          654      654           

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[jariy17]

Does gateway have a seperate unit test for this? Can this be tested within the handler tests?

[nborges-aws]

gateway tests this via unit tests also: src/core/gateway.test.ts:65

[jariy17]

export type ListBatchInsightsResponse = Omit<ListBatchEvaluationsResponse, "batchEvaluations"> & {
batchEvaluations: BatchEvaluationSummary[];
};
I think this will remove all of results

[nborges-aws]

export type ListBatchInsightsResponse = Omit<ListBatchEvaluationsResponse, "batchEvaluations"> & { batchEvaluations: BatchEvaluationSummary[]; }; I think this will remove all of results

@jariy17 This doesn't remove all results. It's a shortcut to avoid adding ?? [] at all call sites. I can remove and add the optional check to all the call sites if this is too confusing