Add sx documentation app (sx.rose-ash.com)

New public-facing service documenting the s-expression rendering engine.
Modelled on four.htmx.org with violet theme, all content rendered via sx.

Sections: docs, reference, protocols, examples (live demos), essays
(including "sx sucks"). No database — purely static documentation.

Port 8012, Redis DB 10. CI and deploy.sh updated with app_dir() mapping
for sx_docs -> sx/ directory. Caddy reverse proxy entry added separately.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitea/workflows/ci.yml

@@ -58,13 +58,22 @@ jobs:
               fi
             fi
 
-            for app in blog market cart events federation account relations likes orders test; do
+            # Map compose service name to source directory
+            app_dir() {
+              case \"\$1\" in
+                sx_docs) echo \"sx\" ;;
+                *) echo \"\$1\" ;;
+              esac
+            }
+
+            for app in blog market cart events federation account relations likes orders test sx_docs; do
+              dir=\$(app_dir \"\$app\")
               IMAGE_EXISTS=\$(docker image ls -q ${{ env.REGISTRY }}/\$app:latest 2>/dev/null)
-              if [ \"\$REBUILD_ALL\" = true ] || echo \"\$CHANGED\" | grep -q \"^\$app/\" || [ -z \"\$IMAGE_EXISTS\" ]; then
+              if [ \"\$REBUILD_ALL\" = true ] || echo \"\$CHANGED\" | grep -q \"^\$dir/\" || [ -z \"\$IMAGE_EXISTS\" ]; then
                 echo \"Building \$app...\"
                 docker build \
                   --build-arg CACHEBUST=\$(date +%s) \
-                  -f \$app/Dockerfile \
+                  -f \$dir/Dockerfile \
                   -t ${{ env.REGISTRY }}/\$app:latest \
                   -t ${{ env.REGISTRY }}/\$app:${{ github.sha }} \
                   .