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

nginx/conf.d/services.conf.template

@@ -114,7 +114,7 @@ server {
     add_header Content-Security-Policy "frame-ancestors 'self' app.${DOMAIN}" always;
 
     location / {
-        set $upstream_code http://code-server-changemaker:8080;
+        set $upstream_code http://code-server-changemaker:8443;
         proxy_pass $upstream_code;
         proxy_set_header Host $host;
         proxy_set_header X-Real-IP $remote_addr;