fix(app): render inline links via UITextView span on iOS (#1257)

AssistantMarkdownLink's native branch wrapped its children in a plain RN
<Text>. On iOS that <Text> sits inside the paragraph's native UITextView
and is not hoisted into a UITextViewChild, so link text (markdown links,
bare URLs, and inline-code path links) was silently dropped — the same
root cause as the bold/italic/strikethrough fix in this PR.

Route the native link through MarkdownTextSpan so it composes as a
UITextViewChild and stays visible + selectable. MarkdownTextSpan now
forwards onPress/accessibilityRole across platforms: tappable on
Android/web; on iOS react-native-uitextview nulls onPress on the root
native view, so reliable tap-to-open is still tracked by #21 — but
visible, selectable, copyable link text strictly beats an invisible one.

Refs #1253

Co-authored-by: Geoffrey <geoffrey.marc@consulting-for.edenred.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/app/src/components/markdown-text.web.tsx

@@ -1,11 +1,23 @@
 import { useMemo, type ReactNode } from "react";
-import { Text, View, type StyleProp, type TextStyle, type ViewStyle } from "react-native";
+import {
+  Text,
+  View,
+  type StyleProp,
+  type TextProps,
+  type TextStyle,
+  type ViewStyle,
+} from "react-native";
 import { CODE_SURFACE_DATASET } from "@/styles/code-surface";
 
 interface MarkdownTextSpanProps {
   style?: StyleProp<TextStyle>;
   monoSurface?: boolean;
   children: ReactNode;
+  // Web links use the <a>/Pressable path in link.tsx, not this span, so these
+  // are accepted for prop-shape parity with the native variants and forwarded
+  // harmlessly.
+  onPress?: TextProps["onPress"];
+  accessibilityRole?: TextProps["accessibilityRole"];
 }
 
 // react-native-web renders Text as <span>/<div> with `user-select: text`
@@ -13,9 +25,20 @@ interface MarkdownTextSpanProps {
 // react-native-uitextview: its transitive import of codegenNativeComponent
 // pulls in setUpReactDevTools, which doesn't resolve under Metro's web
 // target in dev mode.
-export function MarkdownTextSpan({ style, monoSurface, children }: MarkdownTextSpanProps) {
+export function MarkdownTextSpan({
+  style,
+  monoSurface,
+  children,
+  onPress,
+  accessibilityRole,
+}: MarkdownTextSpanProps) {
   return (
-    <Text dataSet={monoSurface ? CODE_SURFACE_DATASET : undefined} style={style}>
+    <Text
+      dataSet={monoSurface ? CODE_SURFACE_DATASET : undefined}
+      style={style}
+      onPress={onPress}
+      accessibilityRole={accessibilityRole}
+    >
       {children}
     </Text>
   );