feat: active workout editing, pounds, and UI accessibility

[BrandanBurgess]

Summary

Add active-workout editing, imperial weight handling, a focused WCAG 2.2 UI cleanup, and profile-local starter schedule dates.

Ticket

Post-v2 usability follow-up

Why

Members need to adjust an in-progress workout when gym equipment is unavailable, see and enter weights in pounds, and use cleaner, more accessible controls.

Acceptance criteria

• AC-1: An in-progress workout supports add, substitute, remove, reorder, and planned-set edits.
• AC-2: Removing an exercise with logged sets requires confirmation and optimistic-concurrency conflicts refresh the session.
• AC-3: Imperial profiles use pounds across Journal, Progress, Growth, Character, and Settings; new registrations default to imperial.
• AC-4: UI controls meet the documented WCAG 2.2 AA focus, target-size, contrast, status, reflow, and modal-keyboard criteria.
• AC-5: New-member starter schedules use the profile's local date.
• AC-6: Full repository verification passes.

Changes

• Added the active-session workout editor using existing canonical session endpoints.
• Centralized kg/lb conversion while preserving canonical kilogram API storage.
• Updated signed-in unit preference immediately after saving Settings.
• Normalized control sizing, focus treatment, contrast, reduced motion, and narrow-screen layouts.
• Fixed timezone-aware starter schedule seeding and added regression coverage.
• Expanded frontend and Playwright acceptance coverage.
• Updated IMPLEMENTATION_PLAN_V2.md and VERIFICATION_REPORT_V2.md.

Verification

• npm run bootstrap
• npm run openapi:check
• npm run lint
• npm run typecheck
• npm run test — 80 web, 2 client, 144 API tests
• npm run build
• npm run e2e — 9/9 journeys
• npm run verify — PASS, final local run 167.0 seconds

Screenshots

N/A — behavior and responsive/accessibility changes are covered by component tests, Playwright viewport assertions, and axe scans.

Database / migration impact

None.

OpenAPI impact

None. Existing active-session mutation endpoints already cover the feature; generated client parity passes.

Security and privacy

No new secret or public-field exposure. Tenant scoping and immutable completed-session behavior are unchanged.

Deployment impact

Merging triggers main CI, GitHub Pages deployment, and the Render API checks-pass auto-deploy. Production smoke tests are required after both complete.

Risks / follow-ups

• npm ci reports two existing high-severity dependency advisories; dependency upgrades are intentionally outside this focused change.