Add is_temporary flag to archiving metrics

[caddoo]

Description

This PR adds archiving metrics support for identifying temporary archives via a new is_temporary flag

• Why: Analysts need to distinguish archives triggered before a period ends (site timezone) from finalized archives for
  performance analysis and comparisons.
• Core behavior: is_temporary is computed from archive start time vs period end in the site timezone.
• Schema/migration: introduces archiving_metrics.is_temporary with default 0 for existing rows.
• Testing: unit tests cover period types and edge/timezone cases; integration test confirms DB write includes the new column/value.

Checklist

• [✔] I have understood, reviewed, and tested all AI outputs before use
• [✔] All AI instructions respect security, IP, and privacy rules

Review

• Functional review done
• Potential edge cases thought about (behaviour of the code with strange input, with strange internal state or possible interactions with other Matomo subsystems)
• Usability review done (is anything maybe unclear or think about anything that would cause people to reach out to support)
• Security review done
• Wording review done
• Code review done
• Tests were added if useful/possible
• Reviewed for breaking changes
• Developer changelog updated if needed
• New documentation added or existing documentation updated

[sgiehl]

Generally looks fine. Left a small suggestion.
Besides that the whole plugin actually misses some end-to-end tests. So triggering a real archiving and ensuring that the metrics are afterwards correctly stored.
I'm not adding an approval here for now, as bumping the version to 5.8.0-b2 should be done after 5.8.0-b1 🙈

[caddoo]

Generally looks fine. Left a small suggestion. Besides that the whole plugin actually misses some end-to-end tests. So triggering a real archiving and ensuring that the metrics are afterwards correctly stored. I'm not adding an approval here for now, as bumping the version to 5.8.0-b2 should be done after 5.8.0-b1 🙈

Thanks!

I believe e2e is covered from the API level inwards, do you want larger scoped tests? The details about the correct values being stored are handled in other tests.

testArchiveReportsWritesMetricsOnceAndDoesNotWriteAgainWhenReusingDbArchive

[sgiehl]

Note: We need to release b2, once this is merged.