refactor: share automatic optimization trigger policy

[MataM15]

Summary

Share automatic-optimization trigger selection between the GUI and Windows service while preserving existing behavior. This independent contribution is based on upstream main; candidate commit: 516907a.

Related Issue

No exact issue identified.

Changes

• Extract a pure AutoOptimizationPolicy helper used by both hosts.
• Preserve schedule priority, the strict low-memory threshold comparison, and the five-minute cooldown boundary.
• Keep host dispatch, timestamp updates, and concurrency behavior unchanged.
• Add nine focused boundary tests.

Checklist

• My code follows the project’s coding style and conventions.
• I have tested the changes locally.
• I have updated documentation if necessary. No new behavior or configuration is introduced.
• This PR does not introduce any breaking changes.
• I have added unit tests if applicable.

Additional Notes

Standalone hosted Windows validation: Release build with 0 warnings and 0 errors; all 9 selected NUnit tests passed. A compiled threshold mutant produced the expected 3 failures; the source bytes were restored and hash-checked, followed by a successful rebuild and 9 passing tests.

The mutation script and validation workflow remain fork-only and are not part of this PR. This is not a concurrency change or a claim of full-suite coverage. Scope: 5 files, 194 changed lines.