fix(db): skip tombstoned communities in community_hosts enumeration

[olympusbuildz]

The community_hosts_with_operation query selected every row from communities with no deletion_state filter. After a whole-community deletion completes, the row remains as a tombstone (deletion_state = 'tombstone') while awaiting physical retention expiry — this is by design.

Both the NIP-43 maintenance sweep (usage_community_hosts) and the push worker pass these ids to reconcile_nip43_membership_snapshots, which calls publish_nip43_membership_list on each. The community write fence rejects the write, producing a WARN log ("NIP-43 membership reconciliation failed") every ~60s indefinitely — exactly the symptom reported in #7558.

Root cause: missing deletion_state predicate in community_hosts_with_operation (crates/buzz-db/src/store/usage.rs:399).

Fix: filter to archived_at IS NULL AND deleted_at IS NULL AND deletion_state = 'active', matching the archival/deletion predicates already used elsewhere in community.rs.

Regression test: test_community_hosts_excludes_tombstoned_communities verifies a tombstoned community is excluded while an active one is returned.

Verification:

• cargo test -p buzz-db --lib store::usage:: — compiles, new test registered (Postgres tests are #[ignore])
• cargo clippy -p buzz-db -- -D warnings — clean
• cargo fmt --check -p buzz-db — clean
• cargo check -p buzz-relay — compiles

Fixes #7558

[github-actions]

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