Feature: Achievement System — Badges & milestones for players

[mholzi]

Feature

Collectible achievements that reward milestones and special plays.

Concept

Badges awarded for accomplishments across games:

• 🎮 First Timer — Play your first game
• 🎯 Bullseye — Guess the exact year
• 🔥 On Fire — 5-streak in a single game
• 👑 Champion — Win a game
• 🏆 Veteran — Play 10 games
• 💯 Perfectionist — Perfect round (all correct)
• 🎸 Decade Master — Score 90%+ on a decade playlist
• ⚡ Lightning — Fastest answer in a round (<2s)
• 🥷 Thief — Successfully steal points
• 📅 Dedicated — Play 7 days in a row

Why

• Collector motivation drives return visits
• "I only need 2 more badges!" effect
• Visible on player profile → social comparison

Implementation Ideas

• Achievement definitions in const.py
• Check triggers in scoring.py after each round/game
• Store unlocked achievements in stats.json per player
• Badge display on game-over screen and player profile

Effort

~4-6h

Labels

enhancement