mif-docs v0.6.3

Attested release. Artifact verified fail-closed before upload.

Patch release fixing a defect affecting every rendered PDF: every drawn word/line had no space character in its actual text content — visually correct, but a naive text extractor (copy-paste in most PDF viewers, pdftotext without -layout, screen readers, most real-world PDF-to-text pipelines) read the entire document run together with zero separation between every word. Fixed at the single shared text-drawing chokepoint. Line/row boundaries (multi-line code blocks, tables) still naive-extract as one continuous run — tracked separately as #142.