Replace custom code-server (9GB) with upstream LinuxServer image (~1GB)

Drop the custom Dockerfile.code-server that bundled Claude Code CLI,
Python/MkDocs tooling, and build-essential on top of codercom base.
Switch to the already-mirrored linuxserver/code-server image instead.

- Both compose files: use code-server:latest, LinuxServer env vars
  (PUID/PGID/DEFAULT_WORKSPACE), port 8443, /config mount layout
- Nginx configs + templates: proxy to :8443 instead of :8080
- API env default: CODE_SERVER_URL updated to :8443
- build-and-push.sh: remove --include-code-server flag
- upgrade.sh: remove code-server conditional rebuild + registry fallback
- install.sh: add --ignore-pull-failures for optional missing images
- .env.example, CCP templates, bunker-ops template: updated

Bunker Admin

bunker-ops/roles/changemaker/templates/env.j2

@@ -171,7 +171,7 @@ MEDIA_API_PORT={{ cml_media_api_port }}
 MEDIA_API_PUBLIC_URL=http://media-api:{{ cml_media_api_port }}
 
 # --- Docs / Code Server ---
-CODE_SERVER_URL=http://code-server-changemaker:8080
+CODE_SERVER_URL=http://code-server-changemaker:8443
 CODE_SERVER_PORT=8888
 MKDOCS_PREVIEW_URL=http://mkdocs-changemaker:8000
 MKDOCS_PORT=4003