XP thresholds (500→1200→2000→…→11000→+2500/level) drive automatic level
increases. add_xp_with_levelup() replaces bare add_xp() in match
processing: for each level gained it grants level×500 coins and milestone
packs (bronze@5, silver@10, gold@15, rare_gold@20, gold every 5 after).
GET /profile now returns computed level (recalculated from XP so it
stays consistent), xp_to_next_level, and xp_for_next_level so the
dashboard can render a progress bar without a second call.
POST /matches/result response gains level_ups array (empty when no
level-up occurred) with new_level, coins_granted, pack_granted per event.
Four new tests: profile level fields, level_for_xp boundary checks,
level-up event in match result, milestone pack unit test.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
funman300