fix(dashboard): load Service Logs without blocking the dashboard

Closes #417 (closed). Opening Service Logs waited for the initial 30-day InfluxDB query and froze the whole dashboard meanwhile. update is now async and runs the query in a worker thread: the page opens in about 0.1 s instead of about 10 s (1M log rows) and the table fills when the query returns. The query itself is unchanged; speeding it up is a follow-up. 🤖 Generated with Claude Code