updating the playtime frontend with claude only code to replace the one graph with a dumb-bell graph, having each individual map show its players at beginning versus end and also the overall impact of maps + their popularity

discord_verificiation/playtime-frontend/README.md

@@ -16,9 +16,11 @@ Node process; nginx reverse-proxies a subdomain to it.
 - `/` — Overview: concurrent-player population graph (hand-rolled SVG, not
   a charting library — scroll to zoom, drag to pan all the way back to
   2015-07-16, click any point for who was online then), a map-to-map
-  population bar chart (same zoom/pan, pool of 150 maps), and a "recurring
-  window" chart for questions like "who's online 6–15h every Tuesday"
-  (pick days of week + time window + date range)
+  population chart (dumbbell-style: grey dot = population when the map
+  started, colored dot = population when it ended, green/red depending on
+  whether it grew or shrank — same zoom/pan, pool of 150 maps), and a
+  "recurring window" chart for questions like "who's online 6–15h every
+  Tuesday" (pick days of week + time window + date range)
 - `/players` — search players by current/previous name or SteamID (shows
   which old name matched, if any), sortable by recent activity, name, or
   highest playtime
@@ -27,9 +29,16 @@ Node process; nginx reverse-proxies a subdomain to it.
   history (with the map(s) each session overlapped)
 - `/maps` — search maps by name
 - `/maps/[mapname]` — every time period that map was played
-- `/maps/period/[mapId]` — one specific occurrence: players present at any
-  point during it, votes cast (grouped by vote event, since a map could
-  theoretically see more than one), and prev/next map navigation
+- `/maps/impact` — leaderboard ranking maps by how they tend to affect
+  population (average start→end player-count change per occurrence,
+  average retention %, best/worst single session), toggleable between
+  impact and raw popularity (times played), rather than the plain
+  played-in-order list on `/maps`
+- `/maps/period/[mapId]` — one specific occurrence: a zoomed-in population
+  timeline for just that session's window (padded a little on each side so
+  the transition in/out is visible), players present at any point during
+  it, votes cast (grouped by vote event, since a map could theoretically
+  see more than one), and prev/next map navigation
 - `/countries` — every country with at least one player, sorted by player
   count descending
 - `/countries/[code]` — players from that country, sortable by highest
@@ -37,7 +46,9 @@ Node process; nginx reverse-proxies a subdomain to it.
 
 A `favicon.ico` in `app/` is picked up automatically by Next — no config needed.
 
-Every feature from the original planning conversation is now built.
+Every feature from the original planning conversation is now built, including
+the map-population-impact features (dumbbell chart, impact leaderboard,
+per-session zoomed timeline) discussed most recently.
 
 ## Deploying on the Hetzner box