Finish the mobile performance pass

- Cache the model catalog once per user and each conversation's setting
  separately; clear both on logout and after model saves
- Compress hashed assets asynchronously with a byte budget and set Vary
- Memoize message parsing and throttle selection reads
- Debounce draft writes to localStorage
- Keep the composer editor on the page and focused, as before
- Add a bundle budget check and run it in CI
- Show a loading block while sessions load and a workspace avatar in the
  mobile conversation header

src/pages/admin/bots/[bot_id]/(partials)/user-bubble.tsx

@@ -6,6 +6,12 @@ import linkComputerRefs from "@/src/utils/link-computer-refs";
 import { UserMarkdownComponents } from "../(data)/user-markdown-components";
 import { QuotableAttribute } from "../(hooks)/use-message-selection";
 
+/**
+ * Kept module-level: a new array on every render makes `react-markdown`
+ * parse the message again.
+ */
+const RemarkPlugins = [remarkGfm, remarkBreaks];
+
 /**
  * Ink bubble with paper text; inverts in dark mode. The text is markdown
  * (GFM; raw HTML is never rendered) as the composer writes it, a single
@@ -18,7 +24,7 @@ export default function UserBubble({ text }: { text: string }) {
             {...{ [QuotableAttribute]: "" }}
             className="max-w-[80%] min-w-0 gap-2.5! items-stretch rounded-default-lg bg-ink text-on-ink px-4 py-3 text-sm leading-5 break-words"
         >
-            <Markdown remarkPlugins={[remarkGfm, remarkBreaks]} components={UserMarkdownComponents}>
+            <Markdown remarkPlugins={RemarkPlugins} components={UserMarkdownComponents}>
                 {linkComputerRefs({ text })}
             </Markdown>
         </Stack>