Habit ledger

Established once a habit's current streak reaches 21 days. Building = still climbing for the first time (best streak under 21). Rebuilding = had a full 21-day run before, lost it, and is climbing again — same "still building" bucket above, no-guilt: a broken streak is a fresh run starting now. Fragile = current streak is 0 or 30-day adherence is under 60% (needs attention now, overrides Building/Rebuilding, never Established). All computed server-side from the same ledger numbers shown on the Consistency page. Deeper habit coaching — when to add a new one, what triggers/rewards to build it around — comes later via OpenHealthAtlas chat.