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/tools/custom/run-prompt-tool.ts

@@ -0,0 +1,30 @@
+import type { CustomToolPromptConfig } from "@/src/types";
+import fillTemplate from "@/src/utils/fill-template";
+import generateText from "../../text/generate-text";
+
+type Params = {
+    config: CustomToolPromptConfig;
+    args: Record<string, unknown>;
+    envs: { key: string; value: string }[];
+    /**
+     * Its models are used, like the run's.
+     */
+    bot_id?: number | string;
+    workspace_id?: number | string | null;
+    signal: AbortSignal;
+};
+
+/**
+ * Fills the tool's prompt in and answers it with one text model turn (no
+ * tools). Returns the answer.
+ */
+export default async function runPromptTool({ config, args, envs, bot_id, workspace_id, signal }: Params) {
+    const result = await generateText({
+        messages: [{ role: "user", content: fillTemplate({ template: config.prompt || "", args, envs }) }],
+        bot_id,
+        workspace_id,
+        signal,
+    });
+
+    return result.text || "(no answer)";
+}