feat(view-pager): add PageIndicator

[bataevvlad]

Problem

ViewPager gives no indication of how many pages there are or which one is visible; apps that move from tabs to a pager lose that cue (#1355). onOffsetChange reports raw pixels and the consumer onLayout was dropped, so even a hand-rolled indicator could not follow the swipe.

Fix

• New PageIndicator (src/components/ui/viewPager/pageIndicator.component.tsx, exported from the ui barrel): one dot per pageCount, the selected dot wider and coloured by status (default primary). Props: selectedIndex, progress (fractional page position; the dots grow / shrink between pages), onSelect (dot press), dotStyle, dotAccessibilityLabel, appearance. Dots are Pressables with role='button' and aria-selected; test ids @<testID>/dot-<i>.
• Eva and Material mappings: a PageIndicator block (paddingHorizontal / paddingVertical 8, dotWidth / dotHeight 8, dotBorderRadius 4, dotMarginHorizontal 4, dotBackgroundColor background-basic-color-4, selectedDotWidth 16) with a status variant group for selectedDotBackgroundColor (primary default, basic = text-basic-color, control = color-control-default). Inserted before Popover in both files.
• ViewPager now forwards a consumer onLayout (it was swallowed by the internal one). The laid-out view is the content strip, pages x page width wide, so pageWidth = layout.width / pageCount; documented on onLayout and onOffsetChange. Arrows stay app-side (onSelect(index ± 1)).
• Showcase ViewPagerIndicator (end of SHOWCASES): a 4-page pager with a progress-driven indicator (labelled dots) and a danger one; Storybook viewPager.stories.tsx (WithPageIndicator, IndicatorStatuses); a PageIndicator section with the props table in view-pager.mdx.

Verification

• Specs: pageIndicator.spec.tsx (7): one dot per page with the mapped size; selected dot width / status colour / aria-selected; primary and first page by default; progress interpolation between two pages; onSelect with the pressed index via the dot test id; dotAccessibilityLabel; dotStyle merge. viewPager.spec.tsx: consumer onLayout forwarded (fails on master).
• Android emulator (Pixel 7, Eva light, section-ViewPagerIndicator): dots exposed as "Page 1 of 4" ... buttons; pressing dot 3 shows "Page: 3" and TRANSACTIONS; pressing dot 4 shows "Page: 4", "Progress: 3.00", and both indicators highlight the fourth dot (the progress-driven one only after the onLayout fix, which is how the dropped callback was found).
• iOS simulator and yarn e2e:ios: see "iOS verification (2026-09-28)" below.
• Gates: yarn turbo run build --filter=@ui-kitten/components, yarn typecheck:all, yarn lint (0 errors, 50 pre-existing warnings), yarn test --runInBand (75 suites, 1894 tests) pass.

Changeset: @ui-kitten/components minor, @ui-kitten/eva minor, @ui-kitten/material minor.

Closes #1355

iOS verification (2026-09-28)

iPhone 17 simulator (iOS 26.2), debug build on Metro from a clean worktree of this branch, driven with agent-device.

• section-ViewPagerIndicator: swipe left -> Page: 2, Progress: 1.00, both indicators move to the second dot; dot 4 press -> Page: 4, Progress: 3.00; dot 3 press -> Page: 3, Progress: 2.00. Eva/Dark and Material/Dark: dots visible on the level-1 background, selected dot in primary / danger.
• Old ViewPager section: swipe -> Page: 2, ORDERS.
• yarn e2e:ios against a Metro serving this branch (the flags injected into a scratch copy of the scripts; without them agent-device test loads the bundle from :8081): smoke.ad and icon-touchable.ad pass; modal-nested.ad (step 51) and autocomplete.ad fail exactly as on master (both fixed in test(e2e): keep modals inside the snapshot budget #1918). An earlier run reported here had loaded another checkout's bundle from :8081 and did not test this branch.

Android verification (2026-09-28, second pass)

Pixel 7 emulator (API 34), debug build on Metro from a clean worktree of this branch, driven with agent-device.

• section-ViewPagerIndicator: swipe -> Page: 2, Progress: 1.00; dot 4 -> Page: 4, Progress: 3.00; dot 3 -> Page: 3.
• Found while testing: unselected dots used background-basic-color-4, 1.2-1.6:1 against the page in all four theme/mapping combos, nearly invisible in the dark themes. Fixed in 057384a: text-hint-color (2.8-5.0:1), with a spec over the four combinations (fails on the old token). Checked on device in all four combos.
• Old ViewPager: swipe -> Page: 2.
• popover-android.ad is stale on master (its fixed scroll count stops at the List section) and was not a branch check; test(e2e): reach showcase sections through a deep link #1932 replaces the scrolls with a section deep link. The Android replay line previously reported here had also loaded another checkout's bundle from :8081.