docs(wiki): add IX hosting server system article + radio site infra

- New wiki/systems/ix-server.md: IX web host (172.16.3.10) facts, the
  ACG hosted sites table, and a full record of radio.azcomputerguru.com
  (Astro static + React 19 islands; source in projects/radio-show/website/;
  build npm run build -> dist -> rsync to cPanel doc root).
- index.md: list the new IX systems article.
- radio-show.md: fix the stale "ix-server.md may not exist" backlink.
- memory reference_radio_website.md: add stack detail (React islands,
  wavesurfer/fuse, node>=22) + pointer to the new wiki article.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

wiki/projects/radio-show.md

@@ -199,7 +199,7 @@ IX server access: paramiko with `look_for_keys=False, allow_agent=False`. Tailsc
 ## Backlinks
 
 - `wiki/systems/jupiter.md` [unverified — may not exist yet] — Jupiter server spec
-- `wiki/systems/ix-server.md` [unverified — may not exist yet] — IX hosting server spec
+- `wiki/systems/ix-server.md` — IX hosting server + the radio website (Astro) build/deploy record
 - `wiki/projects/gururmm.md` — related ACG project
 - `projects/radio-show/audio-processor/README.md` — full pipeline spec and configuration reference
 - `projects/radio-show/post-show-workflow.md` — full post-show content workflow spec