v0.3.3

Fix: auto-generate filename for mdprobe_view content mode

LLMs frequently call mdprobe_view({ content: "# Markdown..." }) without passing filename, causing an error. This release makes filename truly optional:

• When content is provided without filename, a deterministic filename is auto-generated: draft-{hash8}.md in the OS tmpdir
• Same content always maps to the same file (no duplicates)
• Explicit filename still works as before

Before: mdprobe_view({ content: "..." }) → "filename is required when content is provided."
After: mdprobe_view({ content: "..." }) → saves to /tmp/mdprobe/draft-a3f7c912.md and opens in browser