feat: Add a local, CI-enforced public API compatibility check for pocketpay-sdk exports

[simplicityf]

Summary

• Add a shared DataTable<T> component (src/components/DataTable.tsx) with a typed column API, a visible <caption>, and scope="col"/scope="row" attributes on header cells.
• Support optional client-side sorting: sortable columns render as a button and toggle ascending/descending, reflecting the active column via aria-sort ("ascending", "descending", or "none" on other sortable columns). Sorting is stable and never mutates the input data.
• Adopt DataTable on the API keys page (src/app/api-keys/page.tsx) in place of the hand-rolled <ul>/<li> markup, proving the API against sortable label/created-at columns and a non-sortable actions column.
• Document the component in docs/components.md with prop tables and a usage example.

Related Issue

Closes #189

Screenshot

Why

List rendering was hand-rolled and inconsistent across src/app/services/page.tsx, src/app/events/page.tsx, and src/app/api-keys/page.tsx, each with its own markup and header semantics. A shared table primitive makes column behavior (alignment, row/column headers, sorting, aria-sort) consistent and reusable across future list pages.

Test plan

• npm run lint
• npm test (810 passed, 2 skipped, including 16 new tests in src/components/__tests__/DataTable.test.tsx covering caption rendering, scope attributes, row-header vs. td cells, non-sortable columns (no button, no aria-sort), ascending/descending toggling, switching sort columns, numeric vs. lexicographic sorting, stable sort on ties, defaultSortKey/defaultSortDirection, empty data, row/index pass-through, alignment classes, and custom wrapper className)
• npm run build
• Existing src/app/api-keys/page.test.tsx suite passes unchanged against the new table markup