fix(workshop): use shared dayjs formatting

.opencode/changelog/2026-07-06.md

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+# Changes — 2026-07-06
+
+## Workshop Review Cleanup
+- **Why**: Address PR review feedback to use Day.js for date/time logic, split the oversized detail component, and avoid duplicated workshop helpers.
+- **What**: Added shared Day.js relative-time formatting, shared download/vote helpers, extracted detail comments and detail UI sections into separate components, and recorded the Day.js/shared-helper convention in `AGENTS.md`.
+- **Files**: `apps/docs/src/components/store/DetailPage.tsx`, `apps/docs/src/components/store/StoreApp.tsx`, `apps/docs/src/components/store/useStore.ts`, `apps/docs/src/components/store/DetailComments.tsx`, `apps/docs/src/components/store/DetailSections.tsx`, `apps/docs/src/components/store/format.ts`, `apps/docs/src/components/store/store-utils.ts`, `AGENTS.md`
+- **Tests**: `pnpm --filter @homarr/docs typecheck`; `pnpm --filter @homarr/docs lint`; targeted `oxfmt --check` for changed store files.
+- **Docs**: Updated `AGENTS.md` with date/time and shared-helper conventions.
+- **Risks**: Refactor moves code without intentional behavior changes; UI smoke testing in browser not run.