money integrity

[arutsh]

Tracking issue for the budget-fix-341-money-integrity OpenSpec change.

One task group = one sub-issue = one PR, merged before the next group starts. This issue holds no task list of its own — see the sub-issues below.

• Group 1: Exact money storage and arithmetic — money-integrity: Exact money storage and arithmetic (group 1) #342
• Group 2: Atomic budget total tracking — ticket depends on 1 — money-integrity: Atomic budget total tracking — ticket depends on 1 (group 2) #343
• Group 3: Currency code validation on budget writes — ticket depends on 2 — money-integrity: Currency code validation on budget writes — ticket depends on 2 (group 3) #344
• Group 4: Currency list endpoint and full-list picker — ticket depends on 3 — money-integrity: Currency list endpoint and full-list picker — ticket depends on 3 (group 4) #345

Artifacts: openspec/changes/budget-fix-341-money-integrity/ (proposal.md, design.md, tasks.md).