Reduce TimeSliceFactory update allocations

[dexhunter]

Summary

• reuse one read-only filtered data collection for external non-derivative security and consolidator updates
• preserve the separate option, future, and internal-feed update paths
• add focused tests for shared data, derivative isolation, and internal feeds

Performance

The allocation evaluator measures TimeSliceFactory.Create with the same representative packet workload before and after this change:

Version	Allocated bytes/Create
master	31,256
This PR	27,416
Reduction	3,840 (12.285641%)

This is a deterministic allocation metric rather than a CPU timing claim. The candidate repeated at 27,416 bytes/Create in both measured runs.

Public autoresearch record

This optimization was developed through an autoresearch process tracked with Weco.

Validation

• 9 focused TimeSliceTests cases passed in the sealed source-and-test evaluation lane
• exact output snapshots preserved ordering, counts, subscriptions, chains, update targets, deferred input behavior, and empty-collection behavior
• evaluator negative controls rejected out-of-scope edits, reordered or dropped data, and metric instrumentation

This is a partial improvement for #7554; it does not attempt the issue's broader lazy-collection refactor.