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/functions/backend/db/extensions/delete-mcp-server.ts

@@ -0,0 +1,23 @@
+import BunSQLite from "@moduletrace/bun-sqlite";
+import { stopStdioMcpServer } from "@/src/harness/mcp/mcp-stdio-pool";
+import grabMcpServer from "./grab-mcp-server";
+
+type Params = {
+    mcp_server_id: number | string;
+};
+
+/**
+ * Deletes an MCP server (its attachments go with it) and stops it if it's
+ * running here. Its directory, with whatever its setup installed, stays.
+ */
+export default async function deleteMcpServer({ mcp_server_id }: Params) {
+    const server = await grabMcpServer({ mcp_server_id });
+
+    stopStdioMcpServer({ server_id: server.id });
+
+    const res = await BunSQLite.sql({ sql: `DELETE FROM mcp_servers WHERE id = ?`, values: [server.id] });
+
+    if (!res.success) throw new Error(`Couldn't delete the MCP server: ${res.error}`);
+
+    return server;
+}