fix: deleted image wrongfully caching

features/serve_uploaded_images.feature

@@ -23,9 +23,11 @@ Feature: Serving uploaded images as static files
       "application/octet-stream"
     And every response from this handler, success or 404, sets
       "X-Content-Type-Options: nosniff"
-    And every successful response sets a long-lived, public Cache-Control
-      header, e.g. "public, max-age=31536000, immutable", because a stored
-      filename is a UUID and its bytes never change
+    And every successful response sets the Cache-Control header
+      "public, no-cache", so a browser may store the file but must revalidate
+      it before reusing it; a stored filename is a UUID and its bytes never
+      change, but the file can be deleted from the media library, and a
+      long-lived cache would keep showing it
     And an "image/svg+xml" response additionally sets
       "Content-Security-Policy: default-src 'none'; style-src
       'unsafe-inline'; sandbox", so a script embedded in an uploaded SVG
@@ -42,7 +44,7 @@ Feature: Serving uploaded images as static files
       cookie
     Then the response status is 200
     And the response Content-Type is <content_type>
-    And the response Cache-Control is "public, max-age=31536000, immutable"
+    And the response Cache-Control is "public, no-cache"
     And the response X-Content-Type-Options is "nosniff"
     And the response has no Content-Security-Policy header
     And the response body is that file's exact content
@@ -61,7 +63,7 @@ Feature: Serving uploaded images as static files
       with no jwt cookie
     Then the response status is 200
     And the response Content-Type is "image/svg+xml"
-    And the response Cache-Control is "public, max-age=31536000, immutable"
+    And the response Cache-Control is "public, no-cache"
     And the response X-Content-Type-Options is "nosniff"
     And the response Content-Security-Policy is
       "default-src 'none'; style-src 'unsafe-inline'; sandbox"
@@ -128,7 +130,7 @@ Feature: Serving uploaded images as static files
       with no jwt cookie
     Then the response status is 200
     And the response Content-Type is "image/webp"
-    And the response Cache-Control is "public, max-age=31536000, immutable"
+    And the response Cache-Control is "public, no-cache"
     And the response X-Content-Type-Options is "nosniff"
     And the response body is empty