Add 1GB storage cap with staff bypass (#2729)

Re-applies the storage limit from #2713 (reverted in #2715) with an
exception for staff identities so our own account isn't blocked.

app/assets/stylesheets/card-perma.css

@@ -543,4 +543,12 @@
       }
     }
   }
+
+  .card-perma__account-limit-message {
+    background-color: var(--color-canvas);
+    border: 2px solid var(--color-container);
+    border-radius: 4px;
+    margin-block-start: calc(var(--padding-block) / -2);
+    padding: 1ch 2ch;
+  }
 }

app/assets/stylesheets/comments.css

@@ -220,4 +220,12 @@
       display: none;
     }
   }
+
+  .comment-by-system--account-limit {
+    --stripe-color: oklch(var(--lch-blue-lightest));
+
+    .comment__content {
+      padding: 3ch;
+    }
+  }
 }