Export snippets to Markdown

[byteofhoney]

Goal:

Let users export all snippets as a single human readable Markdown file.

User story:

As a user, I want to export my snippets to Markdown so that I can read or share them outside the application.

Tasks

• Implement backend route, e.g. GET /export/markdown.
• Fetch all snippets from the database.
• Loop through snippets and format each into a standard Markdown template (title, language, tags, description, fenced code block).
• Set response headers to trigger an automatic file download.

Acceptance Criteria

• Add a visible "Export as Markdown" button in the UI
• Clicking the export action triggers an immediate file download.
• File downloads without needing further user interaction or opening a new app window.
• Downloaded file renders perfectly on GitHub or any standard Markdown viewer.
• Every snippet includes a proper fenced code block with its respective language tag.
• Gracefully handles empty states if the user has no saved snippets.