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>

sx/entrypoint.sh

@@ -0,0 +1,25 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# No database — skip DB wait and migrations
+
+# Clear Redis page cache on deploy
+if [[ -n "${REDIS_URL:-}" && "${REDIS_URL}" != "no" ]]; then
+  python3 -c "
+import redis, os
+r = redis.from_url(os.environ['REDIS_URL'])
+r.flushdb()
+" || echo "Redis flush failed (non-fatal), continuing..."
+fi
+
+# Start the app
+RELOAD_FLAG=""
+if [[ "${RELOAD:-}" == "true" ]]; then
+  RELOAD_FLAG="--reload"
+  python3 -m shared.dev_watcher &
+fi
+PYTHONUNBUFFERED=1 exec hypercorn "${APP_MODULE:-app:app}" \
+  --bind 0.0.0.0:${PORT:-8000} \
+  --workers ${WORKERS:-1} \
+  --keep-alive 75 \
+  ${RELOAD_FLAG}