feat: structural accessibility for data table

[oleksandrzavarzin-callstack]

Motivation

DataTable's structure was purely visual: bare Views and TouchableRipples with no roles, indices or header relationships, so a screen reader conveyed no table context at all. A user heard "159" with no way to know it was the Calories column of row 3.

Changes

• Web semantics: role="table" with aria-rowcount/aria-colcount, role="row" with aria-rowindex, role="columnheader" with aria-sort, role="cell" with aria-colindex.
• Native fallback: table roles map to no accessibility trait on iOS or Android, so a row is announced as one item: "Dessert, Frozen yogurt, Calories, 159, row 3 of 6". It falls back to per-cell focus when a row holds interactive or non-text content, so nothing becomes unreachable. nativeFocusMode overrides the choice.
• Non-actionable rendering: rows, cells and titles with no touch handler render a plain View.
• Sort state: aria-sort on web, folded into the accessible name on native, with an announcement on change since focus stays on the header. New sortAccessibilityLabels localizes the wording.
• Reanimated: the sort indicator moves off legacy Animated, matching Switch and Checkbox. Reduced motion is suppressed via ReduceMotion.Always instead of a manual snap, and 150ms becomes theme.motion.duration.short3 (same value).
• Pagination: real control names, localizable through one labels prop. Data-dependent values are functions, so pluralization stays with the app's own i18n.
• Columns: optional columns describes width and alignment once instead of repeating style on a title and every cell. New align composes with numeric, which is unchanged and not deprecated.
• Text scaling: numberOfLines is honoured exactly at every font scale; the default is one line at the default scale and unclamped above it.
• Tokens: separators move from surfaceVariant to outlineVariant, matching Divider.

Button gains aria-expanded, needed by the rows-per-page anchor which never reported that it opens a menu.

Breaking changes

Rows, cells and titles without a touch handler render a plain View. They lose the ripple, the web hover background and keyboard focus, and no longer report a disabled state.

// Before (v5): announced as a disabled control
<DataTable.Row>
  <DataTable.Cell>{item.name}</DataTable.Cell>
</DataTable.Row>

// After (v6): pass a handler if the row is meant to be pressable
<DataTable.Row onPress={() => select(item)}>
  <DataTable.Cell>{item.name}</DataTable.Cell>
</DataTable.Row>

Other important changes:

• Rows are announced as a single item on native, and need rowCount and firstRowIndex for correct positions when paginating.
• Pagination default labels changed, so tests querying the old placeholders need updating.
• numeric now applies tabular figures, the one visual change to existing tables.

Related issue

Child of the "Modernize non-standard components" effort; no issue exists yet.

Test plan

• yarn typescript, yarn lint clean
• yarn test 806 passed, 167 snapshots. The 2828-line snapshot is replaced with 8 small per-component snapshots plus named contract assertions, since the old blob is where the aria-disabled regression sat unnoticed.
• Web: verified against the live accessibility tree. Correct roles, counts and indices, aria-sort cycling, and no aria-disabled on any row, cell or title.
• Android: TalkBack on an emulator, cross-checked with adb shell uiautomator dump. Tapping a row focuses that row, each header is its own stop, and a row containing an interactive element (e.g. Checkbox) falls back to per-cell focus.
• iOS: Accessibility Inspector against the Simulator.
• Reduced motion, 200% font scale, and RTL mirroring.

Screenshots: