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/parse-custom-tool-row.ts

@@ -0,0 +1,26 @@
+import type { BUN_SQLITE_COBBLE_CUSTOM_TOOLS } from "@/db/types/db";
+import type { CustomToolRecord } from "@/src/types";
+import parseJsonColumn from "./parse-json-column";
+
+type Params = {
+    row: BUN_SQLITE_COBBLE_CUSTOM_TOOLS;
+};
+
+/**
+ * A `custom_tools` row with its JSON columns read.
+ */
+export default function parseCustomToolRow({ row }: Params): CustomToolRecord {
+    return {
+        id: Number(row.id),
+        name: row.name || "",
+        description: row.description || "",
+        parameters: parseJsonColumn<Record<string, unknown>>({
+            text: row.parameters,
+            fallback: { type: "object", properties: {} },
+        }),
+        all_bots: row.all_bots == 1,
+        enabled: row.enabled != 0,
+        kind: row.kind || "prompt",
+        config: parseJsonColumn<Record<string, unknown>>({ text: row.config, fallback: {} }),
+    } as CustomToolRecord;
+}