fix(nginx): cache and compress the duckdb-wasm asset

The wasm engine is the single largest asset in the build (39,362,651 bytes) but
the immutable-cache location regex did not include `wasm`, so on the
Docker/nginx path it got no Cache-Control at all, and no gzip directive existed
anywhere -- nginx's default gzip_types is text/html only, so it shipped
uncompressed on every cold load.

Verified against nginx:alpine (1.31.3) with the real dist/ mounted:
`nginx -t` passes, and the wasm now returns Content-Type: application/wasm,
Content-Encoding: gzip, Cache-Control: public, max-age=31536000, immutable --
8,766,496 bytes on the wire instead of 39,362,651.

Dynamic gzip rather than gzip_static because the Vite build emits no
pre-compressed .gz files.

nginx.conf

@@ -37,12 +37,32 @@ server {
     root /usr/share/nginx/html/crdc-demo/;  # Adjust if base is different
     index index.html;
 
+    # Compress text assets and — most importantly — the duckdb-wasm engine,
+    # which is ~39MB uncompressed and ~8.8MB gzipped. Without this it ships
+    # uncompressed on every cold load. Dynamic gzip rather than gzip_static
+    # because the Vite build emits no pre-compressed .gz files.
+    gzip on;
+    gzip_vary on;
+    gzip_min_length 1024;
+    gzip_proxied any;
+    gzip_comp_level 6;
+    gzip_types
+        text/plain
+        text/css
+        application/javascript
+        text/javascript
+        application/json
+        image/svg+xml
+        application/wasm;
+
     location / {
         try_files $uri $uri/ /index.html;
     }
 
-    # Civilytics design tokens: immutable cache headers for static assets
-    location ~* \.(js|css|png|jpg|jpeg|gif|svg|woff2|ttf)$ {
+    # Civilytics design tokens: immutable cache headers for static assets.
+    # `wasm` belongs here too — the duckdb engine is content-hashed by Vite and
+    # is by far the largest asset in the build, so it must not be re-fetched.
+    location ~* \.(js|css|wasm|png|jpg|jpeg|gif|svg|woff2|ttf)$ {
         expires 1y;
         add_header Cache-Control "public, max-age=31536000, immutable";
         try_files $uri =404;