Use stored SITE_DOMAIN as default in Caddy domain prompt

lib/common.sh: configure_caddy_for_service now pre-fills the domain prompt
with $DEFAULT_SUBDOMAIN.$SITE_DOMAIN when a site domain has been configured
(setup.sh configure / ~/docker/.config). No more typing the full domain for
every service — just press Enter to accept the default.

services/mattermost.sh: remove redundant custom Caddy/domain block added in
the previous commit. MATTERMOST_SITE_URL is already computed from SITE_DOMAIN
before configure_caddy_for_service is called, so the simple call is sufficient.

https://claude.ai/code/session_014CCYqVwW6d6f5dw1qRokYt

lib/common.sh

@@ -297,10 +297,16 @@ configure_caddy_for_service() {
 
     echo ""
     echo "Enter the full domain for $SERVICE_NAME:"
-    echo "  Examples: $DEFAULT_SUBDOMAIN.example.com, $DEFAULT_SUBDOMAIN.yourdomain.com"
+    local _default_domain=""
+    if [ -n "$SITE_DOMAIN" ] && [ "$SITE_DOMAIN" != "example.com" ]; then
+        _default_domain="$DEFAULT_SUBDOMAIN.$SITE_DOMAIN"
+        echo "  Default: $_default_domain"
+    else
+        echo "  Examples: $DEFAULT_SUBDOMAIN.example.com, $DEFAULT_SUBDOMAIN.yourdomain.com"
+    fi
     echo ""
     local SERVICE_DOMAIN=""
-    prompt_text "Domain:" "" SERVICE_DOMAIN
+    prompt_text "Domain [${_default_domain:-required}]:" "$_default_domain" SERVICE_DOMAIN
     if [ -z "$SERVICE_DOMAIN" ]; then
         echo "  ⚠ No domain provided, skipping Caddy configuration."; return 0
     fi

services/mattermost.sh

@@ -345,50 +345,9 @@ ENV
     ensure_docker_dir_ownership "$DIR"
 
     # ── Caddy reverse proxy ───────────────────────────────────────────────────
-    # Mattermost's SITEURL must match the public URL for WebRTC (Calls) to work.
-    # If the user configures a Caddy domain here, update SITEURL in .env to match.
-    if [ -d "$DOCKER_DIR/caddy" ]; then
-        local _mm_domain=""
-        prompt_text "Caddy domain for Mattermost (e.g. chat.${SITE_DOMAIN:-example.com}) [skip]:" "" _mm_domain
-        if [[ -n "$_mm_domain" ]]; then
-            # Update SITEURL before wiring Caddy so the running container gets the right value
-            sed -i "s|^MATTERMOST_SITE_URL=.*|MATTERMOST_SITE_URL=https://$_mm_domain|" "$DIR/.env"
-            log_info "SITEURL updated → https://$_mm_domain (WebRTC requires HTTPS)"
-            # Write Caddyfile block directly (configure_caddy_for_service would prompt again)
-            local _caddyfile="$DOCKER_DIR/caddy/Caddyfile"
-            local _bk="$DOCKER_DIR/caddy/Caddyfile.backup.$(date +%Y%m%d-%H%M%S)"
-            [[ -f "$_caddyfile" ]] && cp "$_caddyfile" "$_bk" && log_info "Backed up Caddyfile"
-            if grep -q "^${_mm_domain}" "$_caddyfile" 2>/dev/null; then
-                log_warning "$_mm_domain already in Caddyfile — skipping block write"
-            else
-                cat >> "$_caddyfile" << MMCADDY
-
-# Mattermost
-$_mm_domain {
-    reverse_proxy mattermost:8065
-
-    header {
-        Strict-Transport-Security "max-age=31536000; includeSubDomains; preload"
-        X-Content-Type-Options "nosniff"
-        X-Frame-Options "SAMEORIGIN"
-        Referrer-Policy "strict-origin-when-cross-origin"
-    }
-
-    log {
-        output file /var/log/caddy/${_mm_domain}.log
-        format json
-    }
-}
-MMCADDY
-                docker exec caddy caddy fmt --overwrite /etc/caddy/Caddyfile 2>/dev/null || true
-                if docker exec caddy caddy reload --config /etc/caddy/Caddyfile 2>/dev/null; then
-                    log_success "Mattermost accessible at: https://$_mm_domain"
-                else
-                    log_warning "Caddy reload failed — check: docker logs caddy"
-                fi
-            fi
-        fi
-    fi
+    # SITEURL is already set from SITE_DOMAIN above. configure_caddy_for_service
+    # will pre-fill the domain prompt with chat.$SITE_DOMAIN.
+    configure_caddy_for_service "Mattermost" "mattermost:8065" "chat"
 
     # ── README ────────────────────────────────────────────────────────────────
     write_readme "$DIR" << MD