v1.4.3 — NexGSD branding

Non-breaking. Display brand updated to NexGSD (uppercase acronym, since GSD = Get Shit Done).

Technical identifiers stay lowercase:

• npm package: nexgsd (unchanged)
• CLI command: nexgsd (unchanged)
• Slash commands: /nexgsd-* (unchanged)
• File names: nexgsd-*.md (unchanged)

Only the human-readable brand display changed — no install/code changes needed.

Repo also renamed: NexVar/NexGsd → NexVar/NexGSD (old URL redirects automatically).