a11y(webhooks): add table caption and header scopes

[Dedenwrg]

Closes #480

Summary

Adds semantic table markup to the webhooks list so screen readers can navigate it as a proper data table.

Changes

ResourceList.tsx — new table mode (backward-compatible)

• New optional props: caption, tableHeaders, renderCells
• When all three are provided, renders a <table> with:
  • <caption class="sr-only"> — visually hidden, available to AT
  • <thead> with <th scope="col"> for each column
  • <tbody> with <th scope="row"> on the first cell of every row
• Falls back to the original <ul> list when props are omitted — no breaking change for api-keys or other consumers

WebhooksClient.tsx

• Passes caption="Registered webhooks", tableHeaders={["URL", "Events", "Registered", "Actions"]}, and renderCells to produce the four-column table
• renderRow retained for backward-compat but unused in table mode

Tests

New a11y tests in webhooks/page.test.tsx (5 tests)

• <caption> present with descriptive text
• Column headers carry scope="col"
• Row headers carry scope="row"
• No <table> rendered when list is empty
• Caption has sr-only class

New table-mode tests in ResourceList.test.tsx (12 tests)

• Table renders when caption + renderCells provided
• Caption text and sr-only class
• scope="col" on column headers
• scope="row" on first cell of each row
• <td> for data cells
• Fallback to <ul> when caption or renderCells missing
• Loading/empty states still work in table mode
• Remove dialog integration from table rows

Test output

Test Suites: 56 passed, 56 total
Tests:       632 passed, 632 total

Checklist

• npm run lint — no warnings or errors
• npm test — 632/632 pass
• npm run build — clean
• Structure/semantics only — no data or column changes
• Edge cases covered: empty table, single-row table

[mikewheeleer]

thanks @Dedenwrg! could you add a Closes #<issue> line to the PR description so it links to the issue it resolves? once it's linked we can review and merge. 🙏

[Dedenwrg]

thanks @Dedenwrg! could you add a Closes #<issue> line to the PR description so it links to the issue it resolves? once it's linked we can review and merge. 🙏

Done edited
Closes #480