Build Cobble project structure from the handoff

- Remove the preset document suite (letters, emails, invoices, quotes,
  PDF generation, line items) with its routes, API handlers and tables
- Rebrand to Cobble: site data, Lato, handoff design tokens (light and
  dark) in main.css, brand assets in public/brand, ember stone logo and
  regenerated favicons
- Add bots, bot_messages, bot_tasks and bot_task_steps tables, regenerate
  DB types (BUN_SQLITE_COBBLE_*) and add a sample crew seed (seed:bots)
- Add the chat shell at /admin/bots: rail with pinned coordinator and
  user popover, bottom-anchored conversation with composer, working-on
  panel, and a send-message API scoped to the session user
- Add BotStone and Wordmark components, crew status and relative time
  utils with tests, and update AGENTS.md

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/pages/admin/bots/[bot_id]/(partials)/composer-attach-button.tsx

@@ -0,0 +1,19 @@
+import Button from "@moduletrace/twui/layout/Button";
+import { Plus } from "lucide-react";
+
+/**
+ * Attachments are not designed yet; the control is present but inert.
+ */
+export default function ComposerAttachButton() {
+    return (
+        <Button
+            title="Attachments are not available yet"
+            variant="ghost"
+            color="text"
+            aria-disabled="true"
+            className="shrink-0 p-1! -m-1 text-ink dark:text-ink cursor-not-allowed rounded-default-xs focus-visible:ring-2 focus-visible:ring-ink"
+        >
+            <Plus size={16} aria-hidden />
+        </Button>
+    );
+}