v0.6 — Stateless instance (state-in-backend)
Move all runtime instance state out of local disk and into the configured storage backend, MinIO-style (.minio.sys precedent): a fresh Cairn pointed at the same backend with the same config.json IS the same instance — license, settings, share links, legal holds, peering trust, app passwords, local users all travel with the data. Kills the entire "update wiped my state" bug class found while dogfooding v0.4.x (#136 aftermath: emptyDir /data silently reset license-state.json, shares.json, holds.json et al. on every redeploy). Establishes the crisp config/state line: config = how to find and unlock your data (backend connection, encryption identity, IdP); state = everything else, living with the data, encrypted to keys the customer holds. Inserted 2026-08-07; former v0.6 (closed beta) is now v0.7, former v0.7 (public launch) is now v0.8.
