Ecto schema for the quests table.

Three independent dimensions, so any combination is expressible:

• reset — when progress starts over: "never" (permanent, e.g. an achievement), "daily", "weekly", "monthly", or "interval" with reset_interval_days (biweekly = 14, or any cadence).
• starts_at/ends_at — an availability window ("event" quests). Works with any reset, so a daily can run only during a seasonal window.
• prerequisite_quest_key — must be completed first ("chains"). Works with any reset, so dailies and events can chain too.

Fields

• key — unique slug (e.g. "daily_win_3"); progress rows reference it
• objectives — list of Gamend.Quests.Objective (event/target/params)
• rewards — list of Gamend.Quests.Reward, paid exactly-once
• auto_claim — grant rewards on completion without a claim step
• hidden — details withheld until earned (a teaser); the row still lists
• active — inactive quests never advance and are not listed

Grouping, which has three unrelated forms

• category — a label your UI filters or tabs by. No engine behavior; every quest in a category still lists as its own row.
• group_key (+ group_title, naming the collapsed entry) — many quests, one list entry the player opens. Unordered: every member is live at once and the entry stands for whichever is most worth acting on (52 countries to chart, in any order).
• prerequisite_quest_key — a chain. Also one entry, but because the tiers are ordered and only one is reachable at a time.

A quest may carry both a category and a group key. A chain inside a group collapses as a chain first, then contributes its surviving entry to the group.