feat: add native link pills

[hryhoriiK97]

What/Why?

Opt-in pill presentation for Markdown links on iOS and Android. A link whose markdownStyle.linkVariants entry sets pill is drawn as a rounded label with an optional icon; every other link is unchanged. Refs #860.

feat/link-pills is the integration branch for this feature. It lands on main through this PR; the work itself is reviewed in smaller PRs that target the branch:

• feat: add opt-in native link pill presentation #862 (merged into the branch): the implementation started by @juliusmarminge, plus the rework described in this comment.
• feat(link-pill): add optional icon tint #921: icon tint (pill.iconTintColor), replacing feat: support optional tint for native link pill icons #863.
• feat(ios): add long-press menus for links #923: long-press menus for links (linkContextMenuItems, iOS 17+), replacing feat: add per-link native context menus on iOS #865. Stacked on feat(link-pill): add optional icon tint #921.

CI runs here every time something is merged into the branch.

• Style: pill: true uses the defaults; pill: { label, iconUri, borderRadius, paddingHorizontal, paddingVertical, borderWidth, borderColor, maxWidth } customizes it; omitted, false or null keeps an ordinary link. Colors, underline and font family stay on the link variant.
• Per-link content: the new linkPillContent prop sets the label and icon of individual links by exact URL. It is content, not style, so markdownStyle can stay a stable object while it changes. Per-link content wins over the variant's pill.label / pill.iconUri, which win over the link text.
• Icons: local files and bundled assets show on the first layout. http(s) sources load through the same pipeline as Markdown images, using imageRequestHeaders, and the pill keeps room for them while they load. A source that fails shows no icon and is retried after 30 seconds.
• Layout: a pill wraps as one unit and truncates at the available width or maxWidth. It works in paragraphs, headings, lists, blockquotes and table cells.
• Links that stay ordinary: a link whose text contains an image, inline math, a hard line break or a spoiler. A pill inside an unrevealed spoiler is hidden with the rest of the spoiler.
• Text leaving the view: copy, Markdown/HTML/RTF export, accessibility labels and the iOS selection actions (Look Up, Translate, Share) receive the link's own text and URL.
• Web and macOS: render ordinary links and ignore pill and linkPillContent.

API

<EnrichedMarkdownText
  markdown="Open [src/components/a/long/path/file.ts](https://example.com/files/a/long/path/file.ts)"
  markdownStyle={{
    linkVariants: {
      '^https://example\\.com/files/': {
        color: '#3730A3',
        backgroundColor: '#EEF2FF',
        pill: { iconUri: 'file_icon', borderRadius: 10, maxWidth: 180 },
      },
    },
  }}
  linkPillContent={{
    'https://example.com/files/a/long/path/file.ts': { label: 'file.ts' },
  }}
/>

Docs: docs/MENTIONS.md (pill section), docs/API_REFERENCE.md (linkPillContent), docs/WEB.md, docs/MACOS.md.

Implementation

• iOS: a pill link is one attachment character (ENRMLinkPillAttachment), laid out and drawn by TextKit like images and inline math. The link's rendered text is kept on the attachment and put back by ENRMLinkPillText wherever text leaves the view. ENRMMarkdownTextView does the same for the system selection actions. This replaces the custom text storage and glyph substitution of the first version.
• Android: LinkPillSpan is a ReplacementSpan over the original link text, which stays in the buffer. Widths are prepared per layout thread through a shared helper (prepareWidthAwareSpans), and a span change redraws the pill when its icon arrives or a spoiler over it is revealed.
• Shared: pill is a nested object on the native link variant; linkPillContent is passed like imageRequestHeaders. Measurement caches on both platforms account for link variants and pill content.
• Outside the feature: the Android ImageDownloader now reports a request OkHttp rejects as a failed download instead of throwing into the render. The example's iOS test target inherits only the pods' search paths, because linking the pods into the test bundle loaded every library class twice.
• Packaging: android/src/test is excluded from the npm package (files in package.json). The android folder is published whole, so the unit tests shipped with it; a dry run of npm pack now lists no test files.

Testing

CI passed on the last head of #862 (60896773): RN lint, library build, Android and iOS builds, Android and iOS unit tests. The branch holds the same content.

• Jest: link-pill-style.test.ts (style normalization, content normalization and equality).
• Android: 38 Robolectric tests in LinkPillSpanTest.kt.
• iOS: 19 XCTest cases in ENRMLinkPillAttachmentTests.mm, now registered in the example's test target and run by CI.
• Manual: iOS simulator (iPhone 17, iOS 26.5) and an Android emulator, with a local demo screen that is not part of this PR. Checked rendering in every block type, remote icons arriving late, a failing icon, and spoiler reveal.

Not covered: drag-and-drop of a selection containing a pill on iOS, and Maestro E2E. After main was merged into the branch, the on-device check was repeated only for rendering on Android.

PR Checklist

• Code compiles and runs on iOS
• Code compiles and runs on Android
• Updated documentation/README if applicable
• Ran example app to verify changes
• E2E tests are passing
• Required E2E tests have been added (if applicable)

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