Adaptive auto-refresh

Replaced the fixed 10/30/60-second refresh picker with a single toggle. Dash0 now keeps every chart and table fresh at the right cadence automatically.

Key improvements:

• Charts refresh in step with their own resolution (high-resolution charts update frequently, hour-wide charts update calmly)
• Explorer tables (logs, traces, metrics, resources) pause refreshing while you're scrolled into the data and resume when you return to the top
• Polling pauses when you switch to another browser tab
• Auto-refresh steps aside when time range is locked to a fixed window
• Result: fresher dashboards with less noise, fewer wasted queries, and nothing shifting under your cursor