fix(app): make markdown links tappable on iOS (#1334)

* fix(app): make markdown links tappable on iOS

A markdown link's label renders as nested React elements
(link > textgroup > text -> MarkdownInheritedText spans). The link's
onPress was placed on the wrapping UITextView span, but
react-native-uitextview only attaches onPress to the *string* children
it converts into tappable RNUITextViewChild nodes - element children
pass through untouched, so the handler never reached a node the native
tap recognizer could fire. Link text stayed visible and selectable but
dead to taps; web links never opened.

Thread the link's press handler down to the leaf text spans via a new
AssistantLinkPressProvider so it lands on the real tappable string
nodes. MarkdownInheritedText consumes the context and forwards onPress
to its MarkdownTextSpan; null outside a link, so ordinary text is
unaffected. Gated to iOS - Android forwards onPress through nested
<Text> already, and web uses the <a> path.

* refactor(app): export useAssistantLinkPress from module index

Import it through the assistant-file-links public surface instead of
reaching into the internal link-press-context file, matching the rest of
message.tsx. Addresses Greptile review feedback on #1334.

---------

Co-authored-by: Kevin Aspesi <kevinaspesi@Kevins-Mac-mini.local>

packages/app/src/assistant-file-links/link.tsx

@@ -1,5 +1,6 @@
 import { useMemo, useState, type CSSProperties, type MouseEvent, type ReactNode } from "react";
 import {
+  Platform,
   Pressable,
   Text,
   View,
@@ -10,6 +11,7 @@ import {
 import { StyleSheet } from "react-native-unistyles";
 import { isNative, isWeb } from "@/constants/platform";
 import { MarkdownTextSpan } from "@/components/markdown-text";
+import { AssistantLinkPressProvider, type AssistantLinkPress } from "./link-press-context";
 import { Shortcut } from "@/components/ui/shortcut";
 import { Tooltip, TooltipContent, TooltipTrigger } from "@/components/ui/tooltip";
 import { useStableEvent } from "@/hooks/use-stable-event";
@@ -56,23 +58,42 @@ export function AssistantMarkdownLink({
     () => [style, hovered && { textDecorationLine: "underline" as const }],
     [style, hovered],
   );
+  const linkPress = useMemo<AssistantLinkPress>(
+    () => ({ onPress, accessibilityRole: "link" }),
+    [onPress],
+  );
 
   if (isNative) {
     // Must be a MarkdownTextSpan, not a plain <Text>: on iOS the link renders
     // inside the paragraph's native UITextView, and a plain <Text> nested there
     // is not hoisted into a UITextViewChild, so its text is silently dropped
-    // (the link disappears). The span composes correctly and stays selectable;
-    // onPress is forwarded (reliable tap-to-open on iOS is tracked by #21).
+    // (the link disappears). The span composes correctly and stays selectable.
+    //
+    // Tap-to-open: react-native-uitextview only wires onPress onto the *string*
+    // children it turns into RNUITextViewChild nodes — the element children that
+    // markdown emits for link text pass through untouched, so an onPress placed
+    // here never reaches a tappable native node. We thread it down through
+    // AssistantLinkPressProvider so each leaf text span re-attaches it to its
+    // own string children, where the native tap recognizer can find it. iOS
+    // only: Android forwards onPress through nested <Text> already, and web uses
+    // the <a> path below.
+    const span = (
+      <MarkdownTextSpan
+        accessibilityRole="link"
+        monoSurface={monoSurface}
+        onPress={onPress}
+        style={style}
+      >
+        {children}
+      </MarkdownTextSpan>
+    );
     return (
       <FileLinkHoverTooltip filePath={tooltipPath}>
-        <MarkdownTextSpan
-          accessibilityRole="link"
-          monoSurface={monoSurface}
-          onPress={onPress}
-          style={style}
-        >
-          {children}
-        </MarkdownTextSpan>
+        {Platform.OS === "ios" ? (
+          <AssistantLinkPressProvider value={linkPress}>{span}</AssistantLinkPressProvider>
+        ) : (
+          span
+        )}
       </FileLinkHoverTooltip>
     );
   }