feat(play-next): show why each game was picked

Each card shows a reason line under the game name. Issue #28.

README.md

@@ -26,8 +26,8 @@ To Be Played is split into three repositories:
   Steam avatar and a banner from the most played game of the last two weeks, and an achievement card: unlocked
   total, perfect games, average completion and the 5 games closest to 100 %.
 - **What to play next** (`/play-next`): three backlog picks for a time budget (up to 5 / 15 / 40 h or any) and a mood
-  (story, co-op, chill, action, scary from IGDB; speedrun from speedrun.com), high priority first, reroll without
-  repeats, and "Start playing" in one click.
+  (story, co-op, chill, action, scary from IGDB; speedrun from speedrun.com). Each pick says why: like a game you
+  played a lot, waiting longest, or random. Reroll without repeats, and "Start playing" in one click.
 - **Your stats** (`/stats`): totals and statuses; the pile in hours, in weeks at your pace of the last 90 days and in
   years of full-time work, and its oldest unplayed game; most played and most loyal games; top genres and moods;
   trips to the moon, the longest gaming day, games started but under one hour; finished games per year; games per platform.