audit 3: every per-message question of the send log has its index

Migration 0010 (DDL only; 0009 went to stage 2b). EXPLAIN QUERY PLAN of
every send_log statement showed, beyond M2 as written (stage 2 had already
moved the by-domain counts onto (domain_id, created_at)):

- the tailer's sweep of open rows (every 5 min) and its count scanned the
  table: partial idx_send_log_open (created_at) WHERE status IN ('queued',
  'deferred'), the statuses literal in the statements, ORDER BY +id (else
  SQLite walks the table in id order to skip a sort);
- AttachRefusalLine's NOT EXISTS (... refusal_line = ?1) scanned the table
  for every refusal line: partial idx_send_log_refusal_line, the query
  carrying the index's WHERE; its row found by idx_send_log_rejected
  (status literal, +queue_id) instead of every refusal without a queue id;
- an application's level-2 count went through its domain's index:
  +domain_id in appByLogin;
- a page of one domain's or one application's log sorted all of it:
  idx_send_log_domain_id, idx_send_log_app_login (id order; several domains
  still sort, top-N). idx_send_log_domain stays for the global filter.

The statements are constants and builders (countMessagesQuery,
peakPerHourQuery, listOpenQuery, countOpenQuery, sendLogPageQuery,
attachRefusalLineQuery, limitRefusalsQuery) and
TestSendLogQueriesUseTheirIndexes explains exactly those: the index each
must use, no SCAN of send_log, no sort where none is wanted; the literal
statuses checked against the constants. It replaces the hand-written plan
check of TestLimitRefusalsSince.

Tested on the test server: go vet + go test of 24 packages, make e2e (all
pass) on this tree.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/store/schema_test.go

@@ -107,7 +107,8 @@ func TestBaselineSchema(t *testing.T) {
 	wantIdx := []string{
 		"idx_applications_login_nocase", "idx_dmarc_report_records_report", "idx_dmarc_reports_domain", "idx_dmarc_reports_received",
 		"idx_inbound_spam_log_created_at", "idx_inbound_spam_log_domain_created_at", "idx_inbound_spam_log_domain_id_created_at",
-		"idx_send_log_app_login_created_at", "idx_send_log_created_at", "idx_send_log_domain", "idx_send_log_domain_id_created_at", "idx_send_log_lines_queue_id", "idx_send_log_queue_id", "idx_send_log_rejected",
+		"idx_send_log_app_login", "idx_send_log_app_login_created_at", "idx_send_log_created_at", "idx_send_log_domain", "idx_send_log_domain_id", "idx_send_log_domain_id_created_at",
+		"idx_send_log_lines_queue_id", "idx_send_log_open", "idx_send_log_queue_id", "idx_send_log_refusal_line", "idx_send_log_rejected",
 		"idx_sessions_expires_at",
 	}
 	sort.Strings(wantIdx)
@@ -116,8 +117,8 @@ func TestBaselineSchema(t *testing.T) {
 	}
 
 	var version, appID int64
-	if err := st.db.QueryRow("PRAGMA user_version").Scan(&version); err != nil || version != 9 {
-		t.Errorf("user_version = %d, %v; want 9", version, err)
+	if err := st.db.QueryRow("PRAGMA user_version").Scan(&version); err != nil || version != 10 {
+		t.Errorf("user_version = %d, %v; want 10", version, err)
 	}
 	if err := st.db.QueryRow("PRAGMA application_id").Scan(&appID); err != nil || appID != applicationID {
 		t.Errorf("application_id = %#x, %v; want %#x", appID, err, applicationID)
@@ -193,8 +194,8 @@ func TestOpenMigratesA20Database(t *testing.T) {
 	}
 	defer st.Close()
 	var version int
-	if err := st.db.QueryRow("PRAGMA user_version").Scan(&version); err != nil || version != 9 {
-		t.Errorf("user_version = %d, %v; want 9", version, err)
+	if err := st.db.QueryRow("PRAGMA user_version").Scan(&version); err != nil || version != 10 {
+		t.Errorf("user_version = %d, %v; want 10", version, err)
 	}
 	if ok, err := st.UserExists(); err != nil || !ok {
 		t.Errorf("the user of the 2.0 database: exists = %v, %v", ok, err)