LPM-140 The Sprinting Update
Adds sprint support across the web UI (board + issue detail), TUI kanban, CLI/REPL, and the Beads-backed storage layer.
Changes:
Introduces sprint entities in storage and exposes sprint operations via IssueService.
Updates web board to support backlog vs. sprint columns, sprint selection, and sprint creation routes.
Updates TUI kanban to show backlog + sprint columns and adds sprint selection/creation actions.
Adds MongoDB-backed submission for survey statistics/metrics and introduces MongoDB ObjectID-based participant/task identifiers to support upserts and linking metrics to a participant.
It introduces breaking changes to the exsisting json stat and metric files. Delete the old ones
Changes:
Add internal/storage/MongoStorage and wire pm survey submit / pm start to submit local .pm/*.json files to MongoDB.
Extend stats/metrics models to include MongoDB _id / participant_id fields and add participant ID propagation into task metrics.
Update app initialization to generate ObjectIDs for new participants and expose GetParticipantID() via StatsService.
