[TUTORIAL] Fix quests.json totals (50/100/150/200 → 25/25/25/25) + popup time (90m → ~30m)

[ottovlotto]

Per spec v0.12 Tutorial: The Stadium section.

Two small fixes:

1. quests.json XP totals. Currently shows 50/100/150/200 (= 500 total). Spec says 25/25/25/25 (= 100 total). Update accordingly.
2. Tutorial popup time. Currently shows 90m. Spec says ~30 minutes total. Update accordingly.

Confirm with Todor before merging — spec notes both as "confirm with Todor".