fix(ios): reset typing attributes before importing markdown

[hsource]

What/Why?

When setValue reloads markdown via importMarkdown, iOS assigns plain text using textView.text = .... UITextView stamps the current typingAttributes onto all of that text — including any list paragraph headIndent left over from where the cursor was before blur.

If the user blurs while focused in a nested list item, non-list paragraphs incorrectly pick up that list indent after setValue, even though the parsed markdown and block store are correct.

Reset base typing attributes before ENRMSetPlainText so import only applies block styling from the parsed markdown (via applyFormatting), not stale composer state from the previous cursor position.

Testing

1. Open an editable EnrichedMarkdownTextInput with mixed content: a normal paragraph, a nested list, and another normal paragraph.
2. Place the cursor in a nested list item.
3. Blur the field while JS calls setValue with the current markdown (e.g. on blur to refresh link formatting).
4. Before: non-list paragraphs render with the nested list indent.
5. After: non-list paragraphs stay at normal indent; list items still render at the correct depth.

Tested on iOS

Before	After

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)