Skip sync for existing data and too-recent dates

- Check consumption table before fetching; return early if data exists
- Return "no data to fetch" for dates >= yesterday (not yet available)
- Add sync-month.sh script to sync all days in a month
- Add kill-server.sh script to free port 3000

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

resources/queries.sql

@@ -48,6 +48,12 @@ VALUES (:metering-point-id, :charge-type, :name, :description, :owner,
   :valid-from-date, :valid-to-date, :period-type, :price, :quantity, :position)
 ON CONFLICT (metering_point_id, charge_type, name, owner, valid_from_date, position) DO NOTHING;
 
+-- :name count-consumption-for-date :? :1
+-- :doc Count consumption records for a given UTC time_start
+SELECT count(*) AS cnt
+FROM consumption
+WHERE time_start = :time-start;
+
 -- :name insert-production! :! :n
 -- :doc Insert a production record, skip if already exists
 INSERT INTO production (time_start, hour, kwh)