fix(nginx): stop caching /public static files as 1y immutable

Split the asset cache rule into two locations applied to both the
main and python.anyplot.ai server blocks:

- /assets/* (Vite-fingerprinted) keeps expires 1y + immutable — safe
  because the filename changes on every build
- stable-named files from /public (favicon.svg, logo.svg, og-image.png,
  fonts) drop immutable and get max-age=604800 (1 week), so content
  updates actually propagate instead of sitting behind a 1-year CDN
  lease

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

Author: MarkusNeusinger

app/nginx.conf

@@ -49,12 +49,19 @@ server {
     gzip_types text/plain text/css text/xml text/javascript application/javascript application/xml+rss application/json;
     gzip_static on;
 
-    # Cache static assets
-    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff|woff2|ttf|eot)$ {
+    # Vite-fingerprinted assets — filename changes on every build, safe to cache forever
+    location ^~ /assets/ {
         expires 1y;
         add_header Cache-Control "public, immutable";
     }
 
+    # Stable-named static assets from /public (favicon.svg, logo.svg, og-image.png, fonts)
+    # Short TTL so redeploys propagate within a week; revalidation allowed.
+    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff|woff2|ttf|eot)$ {
+        expires 1w;
+        add_header Cache-Control "public, max-age=604800";
+    }
+
     # Disable caching for index.html
     location = /index.html {
         add_header Cache-Control "no-cache, no-store, must-revalidate";
@@ -154,11 +161,19 @@ server {
     gzip_types text/plain text/css text/xml text/javascript application/javascript application/xml+rss application/json;
     gzip_static on;
 
-    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff|woff2|ttf|eot)$ {
+    # Vite-fingerprinted assets — filename changes on every build, safe to cache forever
+    location ^~ /assets/ {
         expires 1y;
         add_header Cache-Control "public, immutable";
     }
 
+    # Stable-named static assets from /public (favicon.svg, logo.svg, og-image.png, fonts)
+    # Short TTL so redeploys propagate within a week; revalidation allowed.
+    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff|woff2|ttf|eot)$ {
+        expires 1w;
+        add_header Cache-Control "public, max-age=604800";
+    }
+
     location = /index.html {
         add_header Cache-Control "no-cache, no-store, must-revalidate";
         add_header Pragma "no-cache";