feat(points): unlock items, progress bars and skins

Locked items show a progress bar until the goal is reached. Four
CSS-only skins (Pastel, Retro CRT, Cyberpunk, Steam) in skins.css,
light and dark. A skin overrides accent and corners; badges, borders,
frames, effects and game art stay on top. New Platinum shine and
Equalizer effects.

README.md

@@ -34,7 +34,10 @@ To Be Played is split into three repositories:
 - **Pile Points** (`/points`): points for playing games off your pile (start, finish by time to beat, 100 %, month and
   streak bonuses; Core checks proof of play), spent in a small shop on an avatar border, a badge, a premium accent, a
   banner frame, an effect for 100 % games and an animated page or banner background (CSS and SVG, in `effects.css`),
-  shown on the dashboard and the public profile. The balance is in the header. Every effect stands still with the
+  shown on the dashboard and the public profile. Twelve more items are unlock-only: they show locked with a progress bar
+  until a goal is reached (games finished, 100 % games, weeks in a row, months with a smaller pile, months with more
+  play time). Skins (`skins.css`, Pastel, Retro CRT, Cyberpunk bought, Steam unlocked) are full themes made of CSS
+  variables; a skin wins over accent and corners, while badges, borders, frames and effects stay on top. The balance is in the header. Every effect stands still with the
   system setting "reduce motion" or the "Reduce animations" switch in the settings.
 - **Landing page**: next to the community numbers and the top games, three blocks: games per platform, top genres and
   finished games per year of all users.