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/harness/mcp/grab-mcp-dir.ts

@@ -0,0 +1,22 @@
+import { mkdir } from "fs/promises";
+import path from "path";
+import { AppData } from "@/src/data/app-data";
+import grabDirNames from "@/src/utils/grab-dir-names";
+
+type Params = {
+    server_id: number | string;
+};
+
+/**
+ * Where a stdio MCP server runs and its setup installs:
+ * `DATA_DIR/<AppData.McpDataDir>/<id>`, created when missing. On the data
+ * volume in production, so installs survive app updates.
+ */
+export default async function grabMcpDir({ server_id }: Params) {
+    const { DATA_DIR } = grabDirNames();
+    const dir = path.join(DATA_DIR, AppData.McpDataDir, String(server_id));
+
+    await mkdir(dir, { recursive: true });
+
+    return dir;
+}