Refactor reports to share definitions across intervals

tests/test_reports.py

@@ -48,16 +48,14 @@ def sample_reports(tmp_path):
     cfg.write_text(
         """
 - name: hits
-  interval: hourly
   query: |
-    SELECT strftime('%Y-%m-%d %H:00:00', datetime(time)) AS bucket, COUNT(*) AS value
+    SELECT {bucket} AS bucket, COUNT(*) AS value
     FROM logs
     GROUP BY bucket
     ORDER BY bucket
 - name: error_rate
-  interval: hourly
   query: |
-    SELECT strftime('%Y-%m-%d %H:00:00', datetime(time)) AS bucket,
+    SELECT {bucket} AS bucket,
            SUM(CASE WHEN status >= 400 THEN 1 ELSE 0 END) * 100.0 / COUNT(*) AS value
     FROM logs
     GROUP BY bucket