feat(data): complete portable SQL backend parity

Align MySQL and SQLite schemas, migrations, usage, stats, export, and backfill behavior with the shared data contracts. Extend gateway startup and maintenance support across all SQL drivers.

crates/aether-data/runtime/src/backend/maintenance/mysql.rs

@@ -14,11 +14,11 @@ impl MysqlBackend {
             let table_name = maintenance_identifier(table_name)?;
             summary.attempted += 1;
             let statement = format!("ANALYZE TABLE `{table_name}`");
-            if sqlx::raw_sql(&statement)
-                .execute(self.pool())
+            if sqlx::query_as::<_, (String, String, String, String)>(&statement)
+                .fetch_all(self.pool())
                 .await
                 .map_sql_err()
-                .is_ok()
+                .is_ok_and(|rows| mysql_analyze_succeeded(&rows))
             {
                 summary.succeeded += 1;
             }
@@ -26,3 +26,42 @@ impl MysqlBackend {
         Ok(summary)
     }
 }
+
+fn mysql_analyze_succeeded(rows: &[(String, String, String, String)]) -> bool {
+    !rows.is_empty()
+        && rows.iter().any(|(_, _, message_type, message)| {
+            message_type.eq_ignore_ascii_case("status") && message.eq_ignore_ascii_case("ok")
+        })
+        && rows
+            .iter()
+            .all(|(_, _, message_type, _)| !message_type.eq_ignore_ascii_case("error"))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::mysql_analyze_succeeded;
+
+    fn row(message_type: &str, message: &str) -> (String, String, String, String) {
+        (
+            "aether.usage".to_string(),
+            "analyze".to_string(),
+            message_type.to_string(),
+            message.to_string(),
+        )
+    }
+
+    #[test]
+    fn analyze_requires_an_explicit_ok_status() {
+        assert!(mysql_analyze_succeeded(&[row("status", "OK")]));
+        assert!(!mysql_analyze_succeeded(&[]));
+        assert!(!mysql_analyze_succeeded(&[row("note", "skipped")]));
+    }
+
+    #[test]
+    fn analyze_rejects_error_rows_even_when_an_ok_row_is_present() {
+        assert!(!mysql_analyze_succeeded(&[
+            row("Error", "Table does not exist"),
+            row("status", "OK"),
+        ]));
+    }
+}