0.1.9

Add profits API integration with HA statistics and hourly polling
Fetches battery arbitrage and FCR earnings from /api/v1/profits/{port_id}
on startup and every hour (rolling 90-day window), injecting results as
HA external statistics (enion:profit_spot_saving, enion:profit_fcr_down,
enion:profit_fcr_up, enion:profit_total) so historical data and FCR
backfill appear correctly in the Energy dashboard.

Exposes 5 summary sensors for today/month totals. Includes an in-flight
guard to prevent concurrent API calls if the hourly timer fires while a
slow fetch is still pending. 34 new tests cover the API client, coordinator
helpers, statistics injection, and the anti-hammer polling behaviour.

Full Changelog: 0.1.8...0.1.9