fix(release): reflow annotated tag body for clean release-page rendering

Tag bodies are hard-wrapped at ~72 columns (git convention), but GitLab renders single newlines as line breaks, so release pages show mid-sentence breaks. The create-release notes generation now reflows: joins wrapped prose into single-line paragraphs, preserves blank-line paragraph breaks and list items (-, *, 1.), trims leading/trailing blanks. PGP signature still stripped (verifiable via git verify-tag). POSIX awk, busybox-safe for the cli image.

Surfaced on p1-vp-generator's v6.0.0/v6.1.0/v7.0.0 release pages (backfilled + reflowed by hand); this fixes it at the source for every catalog consumer. Cut as v4.0.3; consumers pin @v4.0.3 to adopt.