Build — Activity Tab Filters + Cache + Refresh

What Was Added

Name Filter

Dropdown <select> auto-populated with unique author names after data loads
Sorted alphabetically, shows "All authors (N)" as default
Filtering is instant — re-renders from cached data, no network call
Count updates: "3 of 12 comments" when filtered, "12 comments" when all

Cache

First visit: fetches all 28 sections from Firestore (one API call per section)
Re-visits (switching tabs back): renders instantly from memory — zero network calls
The loadActivity function now checks loaded && allComments.length and skips fetch

Refresh Button

↻ button next to sort toggle — clears cache, re-fetches all sections
Shows "..." while loading, re-enables when done
Resets name filter to "All authors" on refresh
Prevents double-click with fetching guard

Files Changed

index.html — CSS for select/refresh, HTML controls, rewritten Activity Engine

Review

Verified

Name filter dropdown present with onchange handler
Refresh button present with onclick handler
populateNameFilter() called after every fetch completes
Cache works: loadActivity returns cached data on re-visit
refreshActivity clears allComments + loaded flag before re-fetch
No ID conflicts with existing sort toggles
CSS styled to match existing sort button aesthetic