UX solution for users interacting with both column and timestamp filters

[conservationtimothy]

Goal

Show when a column filter, a date filter, or both filters are applied. Closes #685

Screenshots

What I changed and why

• MapFilterControls now tracks columnFilterActive and dateFilterActive separately from popup open state
• A column filter is considered active when the selection has one or more values; a date filter is active when TimestampFilter emits active: true, meaning the month range is not the full span
• Each button uses aria-expanded for the open popup and aria-pressed for the applied filter state
• Active filter buttons show a white ring and an amber badge; both can show simultaneously so an AND of column and date filters is visible even when no popup is open
• Hidden date-slider tooltips use display: none to prevent them from drawing over the column panel

How I convinced myself this is right

Manual testing

What I'm not doing here

This PR does not change how date and column filters combine on the map as that AND already exists.

LLM use disclosure

Grok 4.6

[rudokemper]

Great solution. Thanks.

[conservationtimothy]

Pleasure as always !