Add chronological timeseries with trend

Add option for long term data tab to have all years shown sequentially, not by day-of-year, and add trend line options and temporal aggregations and filters

No files or tests are named. Start at the long term data tab and trace how the current day-of-year series is assembled; clarify the expected chronological view, trend-line choices, temporal aggregations, and filters. Done means the tab supports sequential multi-year data and the requested analysis options.

Written by the indexing model from the issue text.