GO-6803 Fix Set by Relation not finding objects with unactivated properties

[KirillSto]

Summary

• When querying by relation source (e.g. "Set by Relation: Done"), the subscription filter now also matches objects whose type recommends the relation, not just objects that physically have the key in their details
• Adds typesRecommendingRelation() helper that queries the object store for types whose recommendedRelations, recommendedFeaturedRelations, or recommendedHiddenRelations contain the given relation
• The filter becomes FilterExists{Key} OR TypeIn(types recommending relation), with graceful fallback to the original FilterExists-only behavior on errors

Linear

GO-6803

Test plan

• New test "relation source includes objects whose type recommends the relation" — verifies objects without the key but with a recommending type are found, while objects of unrelated types are excluded
• All existing subscription tests pass (go test ./core/subscription/...)
• Database filter tests pass (go test ./pkg/lib/database/...)

🤖 Generated with Claude Code

[github-actions]

New Coverage	46.7% of statements
Patch Coverage	70.4% of changed statements (19/27)

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