Support conjoined tenancy for DCB tags and natural keys

[jeremydmiller]

Summary

• Add tenant_id column to EventTagTable and NaturalKeyTable primary keys when using conjoined tenancy
• Fix NaturalKeyTable foreign keys to mt_streams to include tenant_id (and is_archived when partitioned), resolving the FK mismatch described in Generated DB patch scripts for natural key tables do not account for conjoined multitenancy #4201
• Add tenant_id filtering to all DCB tag queries (QueryByTags, EventsExist, AssertDcbConsistency, FetchForWritingByTags) for proper tenant isolation
• Update tag insert operations (InsertEventTagOperation, InsertEventTagByEventIdOperation, AssignTagWhereOperation, QuickAppendEventFunction) to include tenant_id
• Update NaturalKeyProjection upsert ON CONFLICT clause to include tenant_id

Closes #4201

Test plan

• 9 new conjoined tenancy DCB tag tests (tag query isolation, events exist isolation, aggregate isolation, fetch-for-writing isolation, cross-tenant no conflict, same-tenant conflict detection, schema creation with archived partitioning)
• 8 new conjoined tenancy natural key tests (same key in different tenants, fetch-for-writing isolation, fetch-latest isolation, schema creation with archived partitioning)
• All 24 existing DCB tag tests pass
• All 15 existing natural key tests pass
• All 4 Bug_4190 archived partitioning tests pass
• All 15 quick-append and assign-tag-where tests pass

🤖 Generated with Claude Code