Portfolio: import details from a Markdown file #46

Part of #40. Depends on #45.

Scope

• A downloadable portfolio.md template and a copyable AI prompt, for example: 'Fill this template with my details. Keep every heading exactly as it is. Do not add HTML.'
• A parser that maps the front matter and headings to the shared fields.
• Unknown sections are reported to the student, never dropped silently. HTML or JSX is rejected with a clear message, as src/lib/mdx-safe.ts does for notes.
• The import only fills in the editor; the student reviews and saves. The Markdown file is never rendered as a page.
• Text files only, with a size limit (for example 50 KB).

Done when

Unit tests cover: the template round trip, missing sections, extra sections, HTML rejection, and invalid links.