Mirror external images into our own storage so they render

Bar items added by barcode stored the Open Food Facts image URL
directly. The CSP in next.config.mjs restricts img-src to our own
origin, so the browser blocked those and showed a broken image - the
picture was fine, we just could not display it.

Copy externally-hosted images into MinIO at lookup time and hand back a
/minio-images path instead. That fixes the class rather than the
instance: no CSP entry is needed per image source, the picture survives
the source deleting or reorganising it, and the user's browser never
has to talk to a third party to render their own bar.

Also fixes a latent bug this uncovered: imageUrl was validated with
z.string().url(), which rejects the relative /minio-images/... paths
that uploadImage returns, so saving an uploaded drink image would fail
validation. That matches production having zero drinks with an image.
Both schemas now accept either form.

CSP keeps two third-party entries for OAuth avatars, which the provider
hosts and we only ever receive as a URL at sign-in.

Existing rows were backfilled separately.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

next.config.mjs

@@ -63,7 +63,17 @@ const nextConfig = {
               "default-src 'self'",
               "script-src 'self' 'unsafe-inline' 'unsafe-eval'",
               "style-src 'self' 'unsafe-inline'",
-              "img-src 'self' data: blob: http://localhost:9000 https://*.amazonaws.com",
+              // Product and drink images are mirrored into our own storage and served
+              // from 'self' via /minio-images, so third-party image hosts do not belong
+              // here. The exceptions are OAuth avatars, which the provider hosts and we
+              // only ever receive as a URL at sign-in.
+              [
+                "img-src 'self' data: blob:",
+                "http://localhost:9000",
+                "https://*.amazonaws.com",
+                "https://lh3.googleusercontent.com",
+                "https://avatars.githubusercontent.com",
+              ].join(" "),
               "font-src 'self'",
               "connect-src 'self' http://localhost:9000",
               "frame-ancestors 'none'",