One row per (decky, operation) attempt. State machine:
pending -> running -> succeeded | failed (+ error text). Rows are
append-only after terminal; retries write a new row.
Sibling of DeckyShard rather than a rework -- DeckyShard tracks
runtime container state observed via heartbeat, this tracks
operation lifecycle. New table, UUID PK.
Adds BaseRepository abstract methods (create_lifecycle,
update_lifecycle, get_lifecycle_by_ids, find_open_lifecycle,
sweep_stale_lifecycle) with SQLModelRepository mixin impl.
Backbone for the upcoming 202-Accepted async API.