* fix: use backlinks history for default trends
* simplify backlinks: remove filters, always use history endpoint
Remove the filter UI (status, subdomains, indirect links, exclude internal)
and hardcode defaults across the stack. Replace the conditional
timeseries_summary + timeseries_new_lost_summary fallback with a single
backlinks/history/live call for trend data. This reduces the overview from
5 parallel API calls to 3 and removes all conditional branching.
* improve charts
* fix: refresh backlinks cost docs
