refactor: simplify EventRepository query/purge complexity

[Ferryx349]

Description

This PR simplifies EventRepository by breaking down high-complexity logic in filter construction and retention purge flow.
It refactors applyFilterConditions into smaller helpers for hex and generic tag criteria handling, while preserving SQL behavior.
It also refactors deleteExpiredAndRetained into clearer steps (candidate selection, whitelist handling, purge count mapping).

Related Issue

Fixes- #46

Types of changes

• Non-functional change (docs, style, minor refactor)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my code changes.
• I added a changeset, or this is docs-only and I added an empty changeset.
• All new and existing tests passed.

[changeset-bot]

🦋 Changeset detected

Latest commit: ac60d31

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
nostream	Patch

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[coveralls]

coverage: 65.901% (+0.8%) from 65.108% — Ferryx349:m2 into cameri:main