[Chat] Add chat invite as message embed type (#10728)

src/components/dms/ChatInvite/JoinButton.tsx

@@ -0,0 +1,42 @@
+import {type StyleProp, type ViewStyle} from 'react-native'
+
+import {atoms as a} from '#/alf'
+import {Button, ButtonIcon, ButtonText} from '#/components/Button'
+import {useChatInvite} from './Context'
+
+/**
+ * The join/open action button for a chat invite. Reads the derived action from
+ * `ChatInvite.Root` context. Pass `onPress` to intercept (e.g. to close a
+ * surface before navigating); it runs before the default action. Renders
+ * nothing while loading or when there's no preview to act on.
+ */
+export function JoinButton({
+  onPress,
+  style,
+}: {
+  onPress?: () => void
+  style?: StyleProp<ViewStyle>
+}) {
+  const {action} = useChatInvite()
+
+  if (!action) return null
+
+  return (
+    <Button
+      testID="joinButton"
+      onPress={() => {
+        onPress?.()
+        action.onPress()
+      }}
+      label={action.label}
+      accessibilityHint={action.accessibilityHint}
+      size="medium"
+      color={action.color}
+      disabled={action.disabled}
+      style={[a.w_full, style]}>
+      {action.side === 'left' && <ButtonIcon icon={action.icon} />}
+      <ButtonText>{action.label}</ButtonText>
+      {action.side === 'right' && <ButtonIcon icon={action.icon} />}
+    </Button>
+  )
+}