C01: P1: service/storage foundation

Go implementation tracking epic

Selected stack: Go + Wails v2 + React/TypeScript + SQLite. Implementation starts on the next machine. Each child below is a separate PR; do not implement this epic in one PR.

Child tasks

• C01a: Domain interfaces and fixture services
  • Merged prerequisites: F01b, F03b.
  • Acceptance: R7: typed Go DTOs, canonical IDs, fixture adapter substitution, deadlines/cancellation and structured errors verified without UI or network.
• C01b: Private storage and first migration
  • Merged prerequisites: C01a.
  • Acceptance: R6: XDG paths, 0700/0600 personal storage, transactional migration and failed-upgrade restore tests; oldhelp data is untouched.

Workflow

See TASKS.md, ROADMAP.md, and CONTRIBUTING.md. Aim for 100-400 handwritten changed lines per PR; split above 600 unless inseparable. Merge prerequisites before dependents. Update task evidence and this checklist after each completed PR. Close this epic only when every child passes; optional work can remain deferred.

All tasks are not started. Live game access and publication/merge actions follow the user's explicit authorization. The planning handoff does not claim runtime validation.

Read TASKS.md, ROADMAP.md, and CONTRIBUTING.md first, then confirm prerequisites F01b and F03b before taking either child task. C01a is done when its typed DTO, ID, fixture, cancellation, deadline, and error checks pass; C01b is done when its XDG, permission, migration, restore, and oldhelp-data checks pass. Complete the children as separate PRs and update the checklist.