Switch nginx config to directory mount and add webhook listener

- Move deploy/nginx.conf -> deploy/conf.d/default.conf and mount the
  directory so future config changes can be hot-reloaded with
  `nginx -s reload` instead of a full container restart.
- Add deploy/hook.py: a tiny stdlib HMAC-validated webhook listener that
  runs pull.sh on Gitea push events. Bound to 127.0.0.1:9528 and
  fronted by openresty at /_hook/deploy.
- Add the matching systemd unit at deploy/facere-deploy-hook.service.
- Teach pull.sh the new layout (reload vs. restart vs. compose up -d)
  and self-restart the hook listener if hook.py changes.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

deploy/conf.d/default.conf

@@ -0,0 +1,45 @@
+server {
+    listen 80;
+    server_name web.facere.cc _;
+
+    root /usr/share/nginx/html;
+    index facere.html index.html;
+
+    charset utf-8;
+
+    # Deny access to repo metadata, deploy scripts/configs, and dotfiles
+    location ~ /\.git { deny all; return 404; }
+    location ~ /\.    { deny all; return 404; }
+    location ^~ /deploy/   { deny all; return 404; }
+    location = /deploy-pull.sh { deny all; return 404; }
+
+    location = / {
+        try_files /facere.html =404;
+    }
+
+    location / {
+        try_files $uri $uri/ /facere.html;
+    }
+
+    # CSS/JS/JSX: short cache so future deploys are picked up promptly
+    location ~* \.(?:css|js|jsx)$ {
+        expires 5m;
+        add_header Cache-Control "public, max-age=300, must-revalidate";
+        types { text/css css; application/javascript js; application/javascript jsx; }
+        try_files $uri =404;
+    }
+
+    # Static media: long cache (filenames are stable / change when content changes)
+    location ~* \.(?:png|jpe?g|gif|webp|svg|mp4|webm|woff2?|ttf|otf|ico)$ {
+        expires 7d;
+        add_header Cache-Control "public, max-age=604800";
+        try_files $uri =404;
+    }
+
+    gzip on;
+    gzip_types text/plain text/css application/javascript application/json image/svg+xml;
+    gzip_min_length 1024;
+
+    access_log /var/log/nginx/facere.access.log;
+    error_log  /var/log/nginx/facere.error.log;
+}