feat: use FileInput DS component for file uploads, fix certs volume perms

- Replace inline FileField and native <input type="file"> with
  FileInput from @cameleer/design-system (drag-and-drop, icons, clear)
- Update CertificatesPage and SsoPage to use FileInput + FormField
- Fix /certs volume permissions (chmod 775) so cameleer user can write

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/package-lock.json

@@ -9,7 +9,7 @@
       "version": "0.1.0",
       "hasInstallScript": true,
       "dependencies": {
-        "@cameleer/design-system": "^0.1.42",
+        "@cameleer/design-system": "^0.0.0-snapshot.20260411.fd08d7a",
         "@logto/react": "^4.0.13",
         "@tanstack/react-query": "^5.90.0",
         "lucide-react": "^1.7.0",
@@ -309,9 +309,9 @@
       }
     },
     "node_modules/@cameleer/design-system": {
-      "version": "0.1.42",
-      "resolved": "https://gitea.siegeln.net/api/packages/cameleer/npm/%40cameleer%2Fdesign-system/-/0.1.42/design-system-0.1.42.tgz",
-      "integrity": "sha512-Cyy+2HsbBPLKRZaSGFxMUvIwI+g8ocdjcojFTGgtq5vrpE/8IYJLgxdtM9+eDoF2Zewk7MrBzfpNqjEYlQO3ng==",
+      "version": "0.0.0-snapshot.20260411.fd08d7a",
+      "resolved": "https://gitea.siegeln.net/api/packages/cameleer/npm/%40cameleer%2Fdesign-system/-/0.0.0-snapshot.20260411.fd08d7a/design-system-0.0.0-snapshot.20260411.fd08d7a.tgz",
+      "integrity": "sha512-ehTXpF6U7bZpvqwj/aaZxdD75sDB8zpn1QVQMDzVUmQGH6RMf9O261DiV1agsOSqPNUB9UPVcdzevMo8ooWTFg==",
       "dependencies": {
         "lucide-react": "^1.7.0",
         "react": "^19.0.0",