perf: skip and cache color computations in TouchableRipple and Chip (#4946)

[ErfanBagheri404]

Fixes #4946

Changes

TouchableRipple - hoverColor is a web-only style (used only in state.hovered), but the color(calculatedRippleColor).fade(0.5).rgb().string() chain ran on every render of every TouchableRipple child, including on iOS/Android where the result was never read. Wrapped in React.useMemo gated by Platform.OS === 'web', so native skips the entire computation. TouchableRipple wraps buttons, list items, etc - this is one of the most-rendered components in the library.

Chip helpers - color(selectedColor).alpha(0.29).rgb().string() ran per Chip per render when a custom selection color was set. Replaced with a module-level Map cache (getSelectedColorBorder) keyed by the input color string, so the parse+alpha+stringify chain runs once per unique color and is reused on subsequent renders.

Benchmark (color@3.1.2)

Chain	per call
.alpha(0.29).rgb().string()	~1.9 µs
.fade(0.5).rgb().string()	~2.2 µs
.isLight()	~0.46 µs

For a 30-item settings list where every row is wrapped in TouchableRipple: ~61 µs per parent re-render was spent computing hoverColor on native - pure dead work. After this change: 0.

What was already done upstream

The issue's original file list (Divider, List.Item, Appbar.Action, TextInput helpers) was stale - those sites were already fixed in recent commits. Only TouchableRipple and Chip remained.

Verification

• jest - Chip: 27/27, TouchableRipple: 5/5
• tsc -b - clean
• eslint - clean