Add MCP servers and custom tools for bots

Two new settings pages, MCPs and Tools. Super admins define them; super
admins and admins attach them to bots, to workspaces (every bot there),
or to every bot. Bots get them in chat replies and tasks.

- Custom tools: a JSON-schema of arguments plus an HTTP request, a script
  on the bot's computer, or a prompt, templated with {{args.x}} and
  {{env.KEY}}, secrets redacted from results.
- MCP servers: remote (URL and headers) or stdio commands run on the host
  with a setup command and an isolated env, in a per-process pool. Tools
  are listed into a cache and connect on first call.
- Add, edit, access and try open in modals.
- Markdown, JSON and command fields use twui's AceEditor (CodeEditor),
  its scripts loaded on demand.

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

src/components/general/computer-icon-tile.tsx

@@ -1,13 +1,9 @@
-import Span from "@moduletrace/twui/layout/Span";
 import { Monitor } from "lucide-react";
+import IconTile from "./icon-tile";
 
 /**
  * A computer's avatar in lists: the monitor icon on a small tile.
  */
 export default function ComputerIconTile() {
-    return (
-        <Span className="size-8 shrink-0 flex items-center justify-center rounded-default-sm border border-solid border-hairline bg-paper">
-            <Monitor size={16} aria-hidden />
-        </Span>
-    );
+    return <IconTile Icon={Monitor} />;
 }